SURFACES
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_______________________________________________________________________ Copyright © 2005 Surpac Minex Group Pty Ltd. All rights reserved.
This software and documentation is proprietary to Surpac Minex Group Pty Ltd.
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While every precaution has been taken in the preparation of this manual, we assume no responsibility for errors or omissions. Neither is any liability assumed for damage resulting from the use of the information contained herein. All brand and product names are trademarks or registered trademarks of there respective companies.
About This Manual
This manual has been designed to provide a practical guide to the many uses of the software. The applications contained within this manual are by no means exhaustive as the possible uses of the software are only limited by the user’s imagination. However, it will give new users a starting point and existing users a good overview by demonstrating how to use may of the functions in Surpac Vision. If you have any difficulties, or questions whist working through this manual feel free to contact your local Surpac Minex Group Office.
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SURFACES
FILES USED.................. USED................................ ............................ ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................ 4 DISCUSSION................. DISCUSSION... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................ 4 Nomenclature............. Nomenclature... ..................... ..................... ..................... ..................... ..................... ..................... ..................... ..................... ..................... ..................... ..................... .................. ....... 6
DTM CONVENTI CONVENTIONS:................. ONS:............................... ............................ ............................ ............................ ............................ ........................... ........................... ........................... ............. 7 Creating a Digital Terrain Model......................................................................................................... 8 Stringss to act as break lines......................... String lines....................................... ............................ ............................ ........................... ........................... ............................ .................... ...... 8
CREATE A DTM ............. ........................... ............................ ............................ ............................ ............................ ............................ ........................... ........................... ........................... ............. 9 Graphical Creati Graphical Creation........................ on...................................... ............................ ............................ ............................ ........................... ........................... ............................ .................... ...... 9 File Based Creat Creation ion ............. ........................... ............................ ............................ ............................ ............................ ............................ ............................ ........................... ............. 10 Common point check distance............................................................................................................. 11 VALIDATING SURFACES ................................................................................................................. 11
SECTIONING SECTIONIN G A DTM ............. ........................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................ 12 CONTOUR EXTRACT.......................... EXTRACT........................................ ............................ ............................ ............................ ............................ ............................ ............................ ................ 14 ACTIVITIES ACTIVITIE S ............. ........................... ............................ ............................ ............................ ............................ ............................ ........................... ........................... ............................ .................. .... 18 1. 2. 3. 4.
5.I) 5 II) 5 III) 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
CREATE DTM FROM THE FILE TOPO1.STR .............. ............................ ............................ ........................... ........................... ............................ .................. .... 19 CREATE A DTM FROM THE STRING FILE PIT 1.STR USING THE FILE BASED DTM CREATION USING THE .......................... ............................ ............................ ............................ ............................ ........................... ............. 20 BREAKLINE TEST AND SPOT HEIGHTS ............ CREATE A BOUNDARY STRING OF THE PIT TO BE USED IN VOLUME CALCULATIONS .............. ......................... ........... 21 USE THE FUNCTION CUT AND FILL BETWEEN DTM’S FROM THE VOLUMES MENU TO CALCULATE THE SURFACE-TO-SURFACE VOLUME BETWEEN PIT 1.DTM & TOPO1.DTM AND CREATE A ........................... ............................ ............................ ............................ ........................... ........................... ......................... ........... 23 RESULTING VOLUME REPORT ............. CREATE A DTM OF THE FILE DHC2.STR WHICH IS A SURVEY OF DRILL HOLE COLLARS PRIOR TO .......................... ............................ ........................... ............. 25 MINING AND WILL BE USED TO MODEL THE NATURAL SURFACE . ............ CREATE A DTM OF THE FILE PIT2.STR USING SPOT HEIGHTS AND USING THE BREAKLINE TEST ... ...... ..... .. 26 USING THESE TWO FILES, CALCULATE A SURFACE TO SURFACE VOLUME ............. ........................... ........................... ............. 27 APPLYING A BOUNDARY STRING TO TRIM A DTM................. DTM............................... ........................... ........................... ............................ .................. .... 29 SECTION THE PIT BY ELEVATION , CREATING CONTOURS EVERY 10 METES OVER PIT1.DTM .... ........ ......... ....... 32 COLOUR A DTM BY ELEVATION ............ .......................... ............................ ............................ ............................ ............................ ............................ .................... ...... 33 DRAPING A STRING OVER A DTM .............. ............................ ............................ ............................ ............................ ............................ ............................ ................ 35 IMAGE DRAPE .............. ............................ ............................ ............................ ............................ ............................ ........................... ........................... ............................ .................. .... 36 CREATING A FLY THROUGH MOVIE ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 42 USE SOME OF THE TOOLS FROM THE ATTRIBUTES MENU FOR ENHANCING THE DISPLAY OF DTMS. 49 UPPER TRIANGLES OF 2 DTM'S - THIS FUNCTION TAKES TWO DTM'S AS INPUT AND CREATES A NEW DTM, WHICH IS AN UPPER SURFACE COMBINATION OF THE TWO INPUT FILES ........................... ................................. ...... 50 LOWER TRIANGLES OF 2 DTM'S .............. ............................ ............................ ............................ ........................... ........................... ............................ .................. .... 51 CREATE SOLID BY INTERSECTING 2 DTM'S ............. ........................... ............................ ............................ ............................ ............................ ................ 52
REVIEW OF SURFACES................. SURFACES............................... ............................ ............................ ............................ ............................ ............................ ............................ .................... ...... 54
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SURFACES OBJECTIVES • • • •
To learn about Surpac’s graphical file types (*.str & *.dtm). To learn how to create surfaces (DTM’s) How to create, view and manipulate Digital Terrain Models To perform surface-to-surface volume calculations.
FILES USED Files used in this lab exercise are found in the following folder: C:\ SURFACES\DATA
DISCUSSION A digital terrain model is a surface joining adjacent strings. It is formed as a combination of those string lines, and lines joining points on strings.
The joining continues until the surface consists only of non-overlapping triangles. The software chooses the joins to produce the best-conditioned triangles - that is, those closest to equilateral triangles.
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The resulting DTM can then be thought of as an undulating patchwork quilt made of triangular patches.
Therefore a Digital Terrain Models (DTM) is how Surpac models surfaces. Surfaces are used in Surpac for such things as 3D visualization & calculating volumes. Most any superficial feature can be modelled as a DTM: natural topography, lithological contacts, bedrock/overburden contact, or water table are such examples. DTM’s must come from String data. String files contain the raw data, where as DTM files contain a mapping of trios of points in the String file that constitute a triangle. DTM’s are made of triangles, with each point of each triangle matched to a point in the original String file. Consequently DTM files are not valid without the original String files. That is, a DTM file cannot be opened if the original String file of the same name does not exist. Another rule as far as DTM’s are concerned is that DTM’s cannot fold back on themselves. That is, a DTM cannot have multiple Z values for for a given XY coordinate. Therefore you cannot model overhanging or vertical surfaces.
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Once created, if the surfaces are to be used to further processing for volumes or more high end functionality within the surface menu, then the object must be named object 1 trisolation 1. Consider this when creating the surface, as each surface must then be placed in a separate file.
Nomenclature The object you create are numbered by a system analogous to that of string and string segment numbers. string object segment trisolation point triangle When you define an object you explicitly assign it both an object number and a trisolation number. That object is then always referred to by the object and trisolation number originally assigned. The object number may be any in the range of 1 to 32000. The trisolation number may be any positive integer.
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DTM CONVENTIONS: cannot model overhangs or vertical surfaces one surface to a layer spot heights v breaklines
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Creating a Digital Terrain Model Strings to act as break lines Once created, Breakline strings are those strings which represent physical features that you can see in the real world e.g. crest of a pit, a fault in a geological model, a contour. If a string file has been formed correctly, then no breakline strings will cross over other breakline strings, unless the two strings cross at a common point as shown below.
Spot height strings contain random points, which when connected by a string line, do not represent any physical feature ie. randomly surveyed points, borehole collars. When modelling surfaces with DTM's, it is important that no triangles are formed across any breakline strings. If however, the string data consist of spot heights only, then the triangles will be formed in the most robust manner without taking into account the string files between the points.
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CREATE A DTM A digital terrain model can be created in two ways to best suit the data you wish to model. 1. Graphically 2. File Based
Graphical Creation Recall the file you wish to triangulate into graphics Select SURFACES | CREATE DTM FROM LAYER
Selecting APPLY from this form will allow the creation of a surface. Save the file by selecting FILE | SAVE| STRING/DTM or select the save icon NOTE: The graphical creation of a surface will always enforce the breakline test. You cannot specify spot heights and the file must always be saved after creation.
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File Based Creation This function does not require a file to be recalled into graphics. You select the file during the creation process. Select SURFACES | DTM FILE FUNCTIONS | CREATE DTM FROM STRING FILE
Define the string file from which the DTM is to be formed. The resultant DTM file will have the same Location Name and Id Number as the string file it was created from, but have an extension of .dtm.
Are strings to be used as break lines, if so, check the box. The data may contain spot heights as well as string data and if so, if you wish to treat these differently to string lines you must also identify the range of spot height strings.
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Common point check distance Points which are very close together in the string file from which the DTM is being created may sometimes cause problems when creating a DTM where some strings are being used as breaklines. If points are of the order of .005 or closer together this problem may manifest itself. A means of solving this problem is to ensure that points within a small distance of each other have exactly the same X and Y co-ordinates. The common point check distance provides a means of controlling the manner in which the co-ordinates of such points are adjusted. Any points which are within the defined distance of each other are guaranteed to be identical thus eliminating a number of problems before they can occur. Note that it is not possible to make the common point check distance greater than 0.02 as large values may have undesirable side-effects in the final DTM which is created. If you wish to prevent the common point check distance from having any influence on the resultant DTM, set to 0.0.
VALIDATING SURFACES
The function also validates each trisolation of the object. Validation consists of looking for: Duplicate triangles (i.e. identical triangles in the same trisolation) • Invalid trisolation edges (i.e. edges in a trisolation which have more than two • attached triangles). Note that the triangles attached to the invalid edges are highlighted. Self intersecting triangles (i.e. triangles in a trisolation that intersect other • triangles in the same trisolation). If triangles satisfying any of the above are found these are highlighted on the screen in a user chosen colour and the trisolation is evaluated as having been validated as false. If no triangles satisfying the above are found then the trisolation is evaluated as having been validated as true. NOTE: a dtm can have open sided triangles and be valid as it is not a closed surface.
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SECTIONING A DTM This function allows you to create horizontal, vertical or inclined slices through a surface (or solid). The plane of intersection of the slices is defined by entering the Y, X, Z coordinates at each end of a three dimensional axis line and by specifying the interval along that axis at which slices are to be taken. The first slice is taken at the start of the axis and then slices are taken at the specified intervals along the axis until the length of the axis is exceeded. Select SOLID TOOLS
CREATE SECTIONS
File: Pit1.DTM The axis start is the co-ordinates for the starting point of the axis line. The first slice is extracted at this starting point. The axis end requires the ending point of the axis line. Slices are extracted PERPENDICULAR to this defined line by the start and end points. Slices will not be extracted past the axis end point.
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Define the axis line, the co-ordinates shown above. Enter a new layer name to store the sliced range and then name the files which will be created. The distance range is also specified. The form definition below will create: • •
A layer named slice which contains all the sections Individual files named slice10000 (10000 to 11000 in increments of 100)
There are two results produced by this function. The first is a range of string files which contain the extracted sections in section coordinates. These files are saved to disk. The second result is a file which contains the extracted sections in real world coordinates. These sections are automatically displayed on the screen in a different layer. You may then activate this layer and save this file to disk.
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The segments produced from the Slice Object function will have the same string number as the object number from which they were extracted. The segments produced may be open or closed segments. Closed objects will always produce closed segments when they are sliced. Open objects may produce open or closed segments when sliced. Closed objects are significant, because the slices generated from slicing a closed object can automatically be used for further processing where closed segments are required. One reason to slice a 3DM is to show one section at a time through a geological model along with the drill holes for that section posted to it. Each of these sections is represented by a single string file where the ID number of the string file created by the slicing function represents the section Northing, Easting or Elevation.
CONTOUR EXTRACT This function extracts contours from a DTM and then stores them in a string file for viewing or plotting. The contours are created by interpolating line segments across all of the triangles and then joining them into continuous strings. The contours will exactly honour the original data from which the DTM was created. These contours can then be used for plotting or volume calculations and polygon intersections with other string files. If contours are required for volumes, or polygon intersection they must be closed strings. You must ensure that the original DTM is constructed to guarantee this will happen. Usually this will involve adding an extra boundary string enclosing the string data in the DTM but with a Z value just greater than the maximum Z value in the data (in the case of a pit, for example) or just less than the minimum Z value in the data (in the case of a stockpile, for example).
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Select CONTOURING | CONTOUR DTM FILE
Define the DTM to be contoured by entering its Location, ID number and the DTM field to be contoured (e.g. Z, D1, D2 etc.).
Define the method that you wish to create the contours. Interval: The contours to be extracted will be defined by entering an interval with a minimum and maximum contour value. Range: The contours to be extracted will be defined by entering a range. Unlike the Interval method which guarantees that contours will be at integral intervals of the contour interval, this method permits you to define the contour levels of interest precisely. It is therefore possible to create contours at intervals of 2 but starting from a non-integral interval of 2. e.g. 147.5, 149.5 etc.
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This method also permits you to extract contours at irregular intervals thus making it possible to extract contours at values of particular interest.
Define the plot enhancement requirements Create index contour file If you intend to use the contours for plotting, you may wish to be able to plot the index contours (or contours at some specific invterval) in a different colour to other contours. For example, if contours were extracted at intervals of 2, then index contours would probably be at intervals of 10, that is 10, 20, 30, etc.
These index contours may be saved to an Index contour string file thus making it easy to plot the index contours using a different colour on a hardcopy map. If you choose to create an index contour file, then the index contours will not be in the contour string file at all, they will only appear in the index contour file. Produce contour annotations If you choose to create contour annotations then a string file will be created which contains data suitable for use by the Plotting module for labelling the contour strings, at the mid point of the each contour, with the contour values. This string file will consist of pairs of points. Each pair of points will be aligned with a small portion of the contour string, in the middle of the string, with the contour value in the D1 field of the second point in each pair of points.
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String 1 in the annotation string file will contain all the annotation data for the "NORMAL" contours while string 2 will contain the annotation data for the index contours.
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ACTIVITIES 1. Create a dtm from the string file topo1.str using the graphical dtm creation method. 2. Create a dtm from the string file pit1.str using the file based dtm creation using the breakline test and spot heights 3. Create a boundary string of the pit to be used in volume calculations 4. Use the function CUT AND FILL BETWEEN DTM’S from the VOLUMES menu to calculate the surface-to-surface volume between pit1.dtm & topo1.dtm and create a resulting volume report 5. Create a dtm of the file DHC2.str which is a survey of drillhole collars prior to mining and will be used to model the natural surface. ii) Create a dtm of the file pit2.str using spot heights and using the breakline test iii) Using these two files, calculate a surface to surface volume 6. Applying a boundary string to trim a DTM 7. Section the pit by elevation, creating contours every 10 metes over pit1.dtm 8. Colour a dtm by elevation
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PROCEDURE
1.
Create DTM from the file topo1.str
The Create DTM function allows you to create a digital terrain model from any string file loaded in graphics. This creation method will no allow you to turn off the breakline test or to include spot heights within your creation. Therefore always consider any data issues that may arise when creating the dtm from the string file. -Are there any vertical or overhanging surfaces -Do I require the breakline test during creation -Are there any spot heights that must be considered If any of these conditions are present within the data, these can cause problems when creating a DTM. To create a DTM file graphically a) b)
Load the file topo1.str into graphics SELECT | SURFACES | CREATE DTM FROM LAYER
This function will create a DTM from the string file that is loaded into graphics and will automatically apply the breakline test during creation.
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c)
Remember to save the file once created.
2. Create a dtm from the string file pit1.str using the file based dtm creation using the breakline test and spot heights A surface can also be created file based, or not graphically by selecting a file and then determining if spot heights or breakline tests are required. a) Load the file pit1.str into graphics and display the string numbers (ps) to determine if there are any spot height strings. This file does not contain spot height strings and so do not need to be included within this form Select SURFACES | DTM FILE FUNCTIONS | CREATE DTM FROM STRING FILE Do not tick on – Strings to act as break lines • Review how the triangles have formed • Do not save this DTM •
Select SURFACES | DTM FILE FUNCTIONS | CREATE DTM FROM STRING FILE • • •
This time tick on – Strings to act as break lines Review how the triangles have formed Save this DTM
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•
•
The message window informs you of the processing as the DTM is created. The LOG file is a small report containing information about your DTM. The DTM file is saved automatically as 'PIT1.DTM'.
It is important to know that for a DTM to be valid, both the DTM and the STR file must exist. If points are added to or deleted from the string file after the DTM has been created, the DTM is rendered invalid and must be recreated.
For volume calculations to be valid the Break Line Test must always be selected during creation.
3. Create a boundary string of the pit to be used in volume calculations.
• • •
A boundary string file can be used for: delineating cut and fill material for calculating volumes finding the intersection of a fault plane with a surface finding where a pit design breaks the natural surface.
a) Recall the files pit1.dtm and topo1.dtm into graphics. Note that the pit extends past the natural topography. To determine the volume of the pit, we need to know this boundary where the topography cuts the pit design, otherwise our volume estimates will be incorrect. We do this by creating a boundary string of the intersection between both dtms.
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b) Select SURFACES DTM FILE FUNCTIONS Line of intersection between two DTM’s. Once we have this line we can use it to constrain our volumes. Complete the line as shown below.
Select both of the dtm’s which you wish to find the intersection and then define the output file you wish to create. c)
Once this has processed, a message will appear in the message window.
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d) This process can also be completed graphically. Ensure that both the dtm’s are loaded into graphics and then select SURFACES | CLIP OR INTERSECT DTM’S | Line of Intersection between two dtms’ and complete the form as shown below.
This outputs the same results, but the fields can be selected graphically.
4. Use the function CUT AND FILL BETWEEN DTM’S from the VOLUMES menu to calculate the surface-to-surface volume between pit1.dtm & topo1.dtm and create a resulting volume report
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One of the most common uses of DTM's is to calculate volumes. The DTM Volumes function allows you to compute the volume between two DTM surfaces, contained within a boundary string. A DTM of Pit1 and Topo1 already exists, and we can use these files to calculate a surface to surface volume.
a) From the menu Volumes, choose Cut and fill between DTM’s. b) Fill the subsequent form as follows:
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5.i) Create a dtm of the file DHC2.str which is a survey of drill hole collars prior to mining and will be used to model the natural surface. a)
Clear graphics and recall the string file 'DHC2.STR'. This file is a survey of drill hole collars prior to mining and may be used to model the natural surface. Notice that the file consists of one spot height string.
b)
Choose Surfaces DTM File Functions | Create DTM from string file and complete the following form.
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Note that when creating a DTM by the file based method we can turn off the option 'Strings to act as break lines' c)
The resulting is saved as 'DHC2.DTM'.
5 ii) Create a dtm of the file pit2.str using using spot spot heights and using the breakline test a) Load the file pit2.str into graphics and display the string numbers (ps) to determine if there are any spot height strings. The string 9999 are spot spot heights and can be used during the creation of the dtm. b) Select SURFACES | DTM FILE FUNCTIONS | CREATE DTM FROM STRING FILE
c)
The resulting is saved as 'PIT2.DTM'.
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5 iii) Using these these two files, calculate a surface to surface surface volume a)
Choose Volumes -- Net volume between DTMs and enter the parameters as shown below. String #2 of Pit2.str can can be used used as a boundary string for the volume calculation.
b)
complete the form below, this is the output file name for the report.
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The results from the DTM volume calculations can be saved to a csv file and optionally to a boundary string file. This string file contains details of the calculations in the Description Fields. The results that are saved to the D fields and the order in which they are saved are described below. These values can be found starting with t he D1 field. • • • • • • • • •
slope area of first DTM slope area of second DTM (only if 2 DTMs are used) area of boundary segment volume between 2 DTMs (or between the first DTM and datum plane z=0) average thickness (volume/area of boundary segment) total of first quality parameter (if it is used) average value of the first quality parameter (only if it used) total of the second quality parameter (only if it is used) average value of the second quality parameter (only if it is used).
Next you will be prompted to save the modified files. c) Save modified DTM. Because you use a boundary string to calculate DTM volumes, triangles which lie outside the boundary string are deleted. Hence the prompt to save the modified DTM. The first DTM is DHC2 and there is no point in i n saving this file, so simply Apply the blank form.
Once again a prompt to save the modified DTM is presented, this is for the second DTM PIT2. d)
Apply the blank form as we do not need to save this file.
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The volume report results are in the file 'PIT2.NOT', which will be displayed on the screen.
DTM creation is strongly influenced by data integrity. It is advisable before creating DTM's to clean up the string data with the Edit -- layer -- Clean functions. Cleaning duplicate points and cross-overs can identify many data problems prior to DTM creation.
6.
Applying a boundary string to trim a DTM
This function applies a boundary string to trim a DTM. The boundary string can consist of any number of closed segments and may contain clockwise and internal anticlockwise segments, i.e. representing pillars or waste volumes. This function is used to prepare a file for viewing solids modelling or contouring within a restricted area.
a)
Recall the string file 'LEV1665. STR'.
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Rotate the image within graphics to view the file.
This is a pick up of some underground workings. b) Select Inquire Segment properties (alias IDS) and select a number of points on the string, note that the t he pillars are anti-clockwise and the drives are clockwise. c)
Select Surfaces Create DTM from layer and apply the confirmation form.
d)
Save the resultant DTM to a file 'LEV1665'.
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Note that when the DTM was created, no distinction was made between clockwise or anti-clockwise strings. The result is a rather untidy DTM which does not accurately model the original survey data. By using the floor string as a boundary string, the anticlockwise segments will act as areas of exclusionThe DTM Clip function does exactly this. e)
Select Surfaces Clip or intersect DTMs Clip DTM with string
f)
Select a point on the string to perform perform the clipping operation. Save the resultant data to DTM file LEV1665.DTM
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Note how the triangles outside the boundary strings have been clipped. This is one way of beginning to create a 3D model of these underground workings.
7. Section the pit by elevation, creating contours every 10 metes over pit1.dtm a) Recall the file pit1.dtm into graphics. We now wish to extract or create contours by elevation every 10 metres over the pit. b) Plot a grid over the area to determine the minimum and maximum extents of the pit. The elevation of this DTM goes goes from 45 to 245 metres. metres. c)
Select CONTOURING CONTOUR DTM IN LAYER
determine if you wish to contour by interval or range and select a contour layer to output the string file.
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d) If you wish to save the sliced string file, change your active layer to “slice” and then save the file.
8.
Colour a DTM by Elevation
a)
Recall the file PIT1.dtm into graphics
b)
Display colour contours with the Display DTM with colour banding
Viewing the DTM by drawing shells is another method of displaying DTM's. rawing shells and using false colouring of triangles is very similar to contouring your data. You can nominate to draw shells by: • •
specifying the number of bands setting the band width
c) Enter the parameters as shown below and choose Apply. As you have nominated to display bands every 200 ppm, t he image on screen represents the following: • •
blue - 0 to 200ppm green - 200 ppm to 400 ppm and so on
d) Choose Display -- DTM and and enter the parameters as shown shown below.
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9.
Draping a String Over a DTM
Recall the file topo1.dtm into graphic Recall the file dhcollar1.str into graphics Note that the drillhole collars are at an elevation of 300m. To determine the correct elevation of the drill hole, we will “drape” the drill hole collars onto the topography to determine the point of intersection.
Select SURFACES | DRAPE STRING OVER A DTM And select the string to drape over the dtm. Ensure that you uncheck the Interpolate New Points. Note: If you wished for new points to be interpolated between the existing points where the string intersects the edge of a given triangle select “Y”
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10.
Image Drape
This function permits you to apply advanced rendering techniques to Di gital Terrain Models and Solid Models by draping an image i mage stored in a GIF file over the model. This technique is very useful when: •
An aerial photograph has been scanned and saved in a GIF file and you wish to drape it over a DTM of the surface to give a photo-realistic representation of the land surface. This technique requires you to digitise a number of control points, known as registration points in the image and in the DTM. This technique requires some effort to produce reasonable results as matching points in the image and the DTM must be selected with care otherwise the image will not match the DTM very well. The co-ordinates of the control points may be saved to a registration file (.rgf) to simplify future image rendering.
•
You want to display solid models of orebodies with a texture appropriate for rock type which it represents. In this ca se, you require a GIF file of a suitable texture which is then 'tiled' over the model.
Display: EOM_PIT.DTM Choose IMAGE | Drape an Image Image file over a DTM from the FILE menu to display the prompt:
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Select the triangle of interest Select a triangle on the trisolation to which the GIF file is to be applied to display the DRAPE IMAGE OVER A DTM or TRISOLATION form.
The registration file stores the parameters used for registering a GIF file over a DTM so that the image can be made to match the DTM precisely. In addition to the name of the GIF file and the filter colour, the registration file records the image coordinates (X
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and Y pixel values) and the corresponding real world coordinates for each of the registration points. If you are using either of the t he tiling options then any file name which you might enter into this field has no effect on the result. A minimum of 3 registration points are required and a maximum of 100 can be used. As more registration points are used, the image will develop a progressively better match with the DTM. Enter a name to create a new registration file. If the registration file named does not exist then it is created and all the details are saved to it after the t he registration points have been defined. If the registration file already exists, the parameters are displayed on the form to permit you to alter them to suit your requirements. Registration files are commonly used to simplify the task of draping an image over a DTM as defining registration points repeatedly for the same image/DTM can be quite time consuming. Image file
This is the GIF file which contains the image to be draped over the DTM. Image draping method The image can be draped over the trisolation using one of two different methods, with each method having two variations. These methods are: Registering the image. This is where the image and the DTM over which it is to be draped are displayed side by side, in different viewports, and matching pairs of points are selected, using the mouse, to control the process of draping the image over the DTM. •
This method is most suitable when the image is of an aerial photograph and the DTM is the land form at the time the photograph was taken. The two variations for this method are: register with new points • This method will use whatever registration points are displayed in the registration points scrolling region and will require more registration points to be defined. You may find that this method will be used a number of times with an image and DTM to progressively improve the match between the image and t he DTM. register with existing points This method will only use the registration points displayed in the registration points scrolling region. If fewer than 3 registration points are present in the scrolling region when you press Apply, you will be required to define some more registration points. •
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•
Tiling the image. This is where the image is given dimensions, in the real world X and Y directions, and the image is tiled over the selected trisolation in tiles of these dimensions.
This method is useful for applying images of different material textures to make solid models of orebodies, for example, appear more realistic. The best results will be achieved with images which have no obvious pattern especially when tiling over solid models as the image may be distorted considerably when folding underneath the solid model. tiling This tiling method simply places the image in tiles of the specified size over the trisolation. •
mirror tiling This tiling method creates a mirror image of every second tile, in both the X and Y directions. •
Define registration points by
When using registration points, you always use the mouse to select the registration point locations in the image. To define the registration point coordinates in the DTM however you may choose from: graphics
The mouse is used to select the location of the registration point on the DTM. Use this method when only approximate locations for the registration points are known or when surface features, roadway intersections for example, are being used.
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keyboard
The coordinates of the registration points are entered into a data entry form using the keyboard. This method is appropriate when the registration points are surveyed targets which are clearly identifiable. Transmission colour
The textured image may be made transparent t ransparent by specifying a transmission colour. This colour is allowed to shine through the textured object when another object falls behind it. Best results can be obtained by using a grey colour. Ambient colour
Some graphics cards adaptors may cause a dimming of t he textured image. This can be countered by specifying an ambient colour that is reasonably light in colour. To cancel the effect of the transmission colour and ambient colour as applied by the IMAGE DRAPE function, you can use either the CLEAR SCREEN or ERASE OBJECTS functions. Image colour filter
The image colour filter works in a manner similar to colour filters in photography. By leaving the colour filter blank, the image is presented in the colours as defined in the image file. Image and Real World coordinates for registration points
If an existing registration file is being used, all the saved parameters, including previously defined registration points are displayed here. There must be a minimum of 3 registration points to register the image to the DTM with wit h the maximum number of registration points being 100. Complete the DRAPE IMAGE OVER A DTM or TRISOLATION form and choose Apply to either drape the GIF image over the selected trisolation or to define registration points for controlling the image registration process. The registration points must now be defined by first selecting, using the mouse, a location in the image. Digitise registration point # in viewport 2 Locate the mouse over the required point in the image and press the mouse button to define the image coordinates for for a new registration point. The following prompt will will be displayed: Digitise registration point # on the DTM in viewport 1 Locate the same point in viewport one and press the mouse.
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After digitising the location of the registration point in the DTM or entering the coordinates of the registration in the DEFINE COORDINATES FOR IMAGE REGISTRATION POINT form, you will be prompted to digitise another registration point. When sufficient registration points have been defined, press Escape to display the REVIEW REGISTRATION POINT COORDINATES form. These are the real world coordinates c oordinates of the corresponding locations for registration points in the DTM. Complete the REVIEW REGISTRATION POINT COORDINATES form and choose Apply to drape the image over the selected trisolation.
Helpful Hints Adjusting the view When defining the registration points either in the image or in the DTM, it is generally necessary to adjust the view by either windowing in or out to find the best location for the registration point. By pressing the ASSIST key, generally F11 you can invoke the Viewer to adjust the view. On exiting from the Viewer you will be prompted to select the point of interest. Resizing the viewports The original viewport containing the selected trisolation is split vertically so the the image and trisolation can be displayed side by side. You may find that the viewports are too small. It is possible to resize and move the active viewport while in the midst of a point digitise action if you find it necessary to alter the viewport size and/or location. If the two viewports overlap then the viewport in which the point must be digitised is brought to the front when necessary. Finding the registration points It is generally easier to locate the position of registration points in the DTM if the image has been rendered with a Light Source before starting the process of defining the registration points. This is because surface features are much more obvious when rendered with a light source and easier to relate to the image. Memory usage Image files, especially if they are large, can consume a considerable amount of memory. To estimate the memory requirements for displaying an image, use the following formula:
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image memory usage = X pixels * Y Pixels * 3 bytes Therefore, an image which is 1000 pixels square will require of the order of 2.5 Mb of memory.
11.
Creating a Fly Through Movie
Now that we have an gif image draped over a DTM, we can now digitise a string to follow and then the view along string function allows you to effectively fly in the direction of a string. This is an excellent method for viewing files. Close all files that are open in graphics. Drag and Drop EOM_PIT.RGF
You will now digitise a line that you wish to fly along. The first step is to set the string number for any digitising that will be done. On the toolbar, click on the design string icon . Set the string number to 500, and then click on the apply button.
Next you will create a new layer for the digitising work to be placed into. On the toolbar, select the layer selection box, and click on the option.
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Enter the name of the new layer and then click on the Apply button. Now any of the digitising will be placed into the layer that was created.
The final step before you start creating your line is to tell Surpac that when you digitise a point it should snap onto the DTM surface. From the toolbar, select the snapping list options and click on the Triangle option. Now you are ready to digitise your line.
On the toolbar, select the icon. Now you can digitise you line. If you wish to window in you can do so at any time, and then start the digitising again by clicking on the icon again. Once you have digitised you line, you should save the string file. Save the file as fly1.str Due to the way the view along string function works, it is a good idea to now lift the string up a certain distance off the DTM surface. This will be done using string maths.
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From the Edit menu, select the String > Maths option. Click anywhere on the digitised string.
Enter the expression as shown, which will lift the string 10 metres above the DTM surface. Another helpful hint will be to smooth the string out. This will remove any very sharp turns in the line.
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From the Edit menu, select the String > Smooth option. When the next form is displayed, click on the Apply button without making any changes. Now save the file again.
View Along String
Now you can run the view along string function. One more step to make the result look even better is to hide the line that you will fly along. When you start the function you only need to see the first point in the line, and as such you can hide the rest. From the Display menu, select the Hide Strings > In a layer option. When the form is displayed, click on the Apply button without making any changes. This will hide all of the strings in the active layer. Next you must display the first point in the fly string.
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From the Display menu, select the Point > markers option.
On the form, only enter the number 1 in the Seg pnt range. This is telling Surpac to only display the first point for the strings in the current layer. In your fly layer, you only have one string so this will be enough. Click on the Apply button. From the View menu, select the Data view options > View along a string option. This will display a form on the screen with the different viewing options.
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Smaller the value the slower the On the form, select the along string option on the left. In the middle of the form, enter display. a camera field width of 100, and the max distance between frames as 5. The bigger this distance, the faster the camera wi ll move along the string. It is also possible to save an image at set points, which would then allow you to link them together as a movie. This would require another piece of software but this can give very good results. Click on the Apply button and then click on the first point of the fly string.
Any time you wish to run the animation again, click on Zoom All, and then go to the View along string function as shown earlier. Saving the images to make a movie
top
Run the view along string function again, but this time on the right of the form, enter a name to be given to images that will be saved at set points.
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You can set the number of pixel to higher resolutions that the default if required.
This will create better images, but will also create bigger files for each image. This option will create a very large number of files, so be careful about how much memory you have free on you computer.
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12. Use some of the tools from the Attributes menu for enhancing the display of DTMs. a) b)
Choose View -- Data view options -- View by bearing and dip Enter a bearing of 45 and a dip of -45.
There are a number of functions for enhancing the display of objects. Try the following icons to display the pit with w ith rendered surfaces. c)
Toggle the Faces on/off icon.
Colouring of triangles is removed. d)
Toggle the Edges on/off icon.
Triangle edges are erased. The image will disappear entirely at this stage but DON'T PANIC. e)
Toggle the Hide on/off icon.
Any triangles behind triangles are removed from display. f) Choose View -- Surface view options -- Perspective projection g) Choose the Light On icon and complete the form as shown below.
h) Toggle the Faces on/off icon back to on. Shading is redrawn. This is a fairly lengthy set of steps that has been made easier with the advent of function icons but has been inproved even further by recording a similar series of steps and using the ability to assign a ssign a SCL macro to an icon. i)
Toggle the Render icon and observe the effect on the displayed DTM.
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This macro render.tcl may be used as an example on how to assign a macro to a toolbar icon, choosing Customise -- Customise menus/toolbars and observing the properties of the Main toolbar will reveal the syntax used.
13. Upper triangles of 2 DTM's - This function takes two DTM's as input and creates a new DTM, which is an upper surface combination of the two input files. Combining a DTM representing a proposed waste stockpile and a DTM representing a topological ground profile to produce a new DTM of the ground profile containing the waste stockpile. a) Recall the two DTM's called `TOPO_DUMP1.DTM' and `DUMP1.DTM', appending them both into the same layer. b)
Go to Surfaces Clip or intersect DTM's Upper triangles of 2 DTM's.
The DTM/DTM UPPER RESULTS RESULTS STORAGE form is displayed. The layer name cannot be the same as any of the current layers.
c) Now follow the prompt by picking each of the DTM's. The order of selection is not important. The program will go through the process of joining the two DTM's, finishing with the statement `Calculations are completed'. You will now be in the layer you specified with the resultant DTM displayed. The result is the waste stockpile surface incorporated into the topographic surface.
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14.
Lower triangles of 2 DTM's
This function takes two DTM's as inputs and creates a new DTM, which is a lower surface combination of the two inputs. Combining a DTM representing a proposed pit design and a DTM representing a topological ground profile to produce a new DTM of the ground profile containing the pit design. 1. Recall the two DTM's called `TOPO1.DTM' and `PIT1.DTM', appending them both into the same layer. These represent a topographic surface and a pit design surface model. 2. Go through exactly the same process as described in the previous exercise except choose Lower triangles of 2 DTM's. The result is a surface representing the pit incorporated into the topography.
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15.
Create solid by intersecting 2 DTM's
This function takes two DTM's as inputs a nd creates a 3DM, which is the volume enclosed between the intersection of the two DTM's. Combining a ground terrain profile with a proposed pit profile to find the volume of material which must be extracted to create the pit. a)
Recall the two DTM's called 'TOPo1.DTM' and 'PIT1.DTM', appending them both into the same layer. These represent a topographic surface and a pit design surface model.
b)
From the Surfaces, Clip or intersect DTM's menu choose Create solid by intersecting 2 DTM's. The DTM/DTM INTERSECT RESULTS STORAGE form is displayed. You are prompted for a layer name in which to display the resultant DTM and the object number to assign to this DTM.
c)
Enter values of your choice, e.g. Layer INTERSECT, object number 3. The layer name cannot be the same as any of the current c urrent layers.
d)
Now follow the prompt by picking each of the DTM's. The upper DTM (topography) must be selected first, followed by the lower DTM (pit).
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The program will go through the process of joining the two DTM's, finishing with the statement `Calculations are completed'. You will now be in the layer you specified with the resultant 3DM displayed. The result is a solid 3DM representing the material that will have to be removed from the designed pit. The image below shows before and after the DTM/DTM Intersection.
e)
Choose Report volume of solids from the Solids Tools menu to create a note file with the volume of the Pit below the topography
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REVIEW OF SURF SURFACES ACES • • •
• •
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String file (*.str) contains spatial data DTM file (*.dtm) contains triangles A DTM is a digital terrain model which is an indexed list of triangles which contain no spatial data DTM file is invalid without an associated string file Triangles are referenced in 3-D space by points in strings and the triangles are formed by connecting groups of three data points together by taking t heir spatial location in the X - Y plane into account. Vertices of triangle coincident with a string point.
Uses: Surface to surface volumes • model weathering surfaces, topography • visualisation • extract sections and plans •
CONVENTIONS 1 DTM surface per file • Breakline v SpotHeight • No vertical or overhanging surfaces • • • • •
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•
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String file hierarchy String Segment Point
DTM file hierarchy Object Trisolation Triangle
Breakline strings are those strings which represent physical features that you can see in the real world e.g. crest of a pit, a fault in a geological model, a contour. No breakline strings should cross over other breakline strings, unless the two strings cross at a common point. The breakline test is an important concept c oncept to understand if DTM is to accurately model terrain Spot heights are random points so will triangulate nearest neighbour
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