The trisolationnumber can be any positive integer. The object number can be any number in the range from 1 to 32000 inclusive. When you define an object, you explicitly assign it both an object number and a trisolation number.The object is then always referred to by this object and trisolation number. L string - objectl segment - trisolationl point - triangle Naming conventionsSurpac assigns numbers to the objects you create by a system similar to that of string and stringsegment numbers: It is not possible to model overhanging or vertical surfaces with a DTM surface. As a result, DTM files are not valid without the original string files.To open a DTM file, you mustalso have access to the original string file of the same name.ĭTMs cannot fold back on themselves.That is, a DTM cannot havemultiple Z values for a given X, Ycoordinate. You can use surfaces for such things as 3D visualisation and for calculating volumes.Almost anysurface can bemodelled as a DTM, including natural topography, lithological contacts,bedrock/overburden contact, or water tables.ĭTMs aremade of triangles, with each point of each triangle matched to a point in the original stringfile. The result is a set of non-overlapping triangles. Triangles are created between points on the strings. Strings and DTMsDigital terrain models (DTMs) are created from strings. Note: This workflow demonstrates the steps in this tutorial. L Surpac v6.3, or later, installed on your computerl the data set accompanying this tutorial L basic knowledge of SurpacIt is recommended that you understand the procedures and concepts from theIntroduction tutorial.
RequirementsBefore you begin this tutorial, you must have: This document introduces the theory behind surfacemodelling processes andprovides detailed examples using the surfacemodelling functions in Surpac.By working through thistutorial, you will gain skills in the construction, use, and modification of DTMs. OverviewSurfacemodelling uses triangulation to create two-dimensional models known as digital terrainmodels (DTMs).
Task: Create solid by intersecting two DTMs 62 Task: Create a lower triangles surface of two DTMs 61 Task: Create an upper triangles surface of two DTMs 61 Task: Drape a non-spot height string over a DTM 55 Task: Drape a spot height string over a DTM 54 Task: Create index contour file with annotations 52 Task: Create DTM contours graphics-based 51 Task: Clip a DTM graphics-based method 44 Task: Create a boundary string using the graphics-based method 34 Task: Create a boundary string using the file-based method 33 Task: Transform a DTM to a different coordinate system 30 Task: Save images of a graphical animation 28 Task: Create a DTM using breaklines and spot heights 19 Task: Create a DTM from spot height data 16 Task: Create a DTM graphics-based method 11
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