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14

It is all very dependent on your needs. You know that TIN is a vector-based representation whereas DEM is represented as a raster from grid of squares. Actually TIN is a type of DEM and derived from the raster DEM. The TIN representation has information about altitude, slope and aspect and you can use them to extract the areas you require. There is an ...


13

A DTM raster can be represented by triangle meshes by finding a set of non-overlapping triangles that covers the entire mesh and approximates the elevation field. There are two different types of triangle meshes that can be used for this purpose: a triangulated regular network (TRN), in which every pixel of the raster is represented by a vertex, and all ...


10

I think you are looking for the Delineate TIN Data Area tool: Redefines the data area, or interpolation zone, of a triangulated irregular network (TIN) based on its triangle edge length.


7

You have a few options: PostGIS 2 has support for TIN and some other 3D objects. GRASS has support via an add-on. See this how-to document. QGIS has an Interpolation plugin (see here) Roll-your-own by importing the GDAL libraries into a 3D modelling package such as Blender (I do it this way a lot because I want interactive 3D model rather than for ...


5

Equal sampling, while easier, means that you can either over-sample parts of the landscape that don't vary much (i.e. smooth slopes or completely flat land), or under-sample parts with a lot of variation (e.g. jagged mountain slopes). That is, you may waste time collecting measurements of no real importance or miss out on important information, respectively. ...


5

We have just created an open source project that will help you do exactly what you want. Tin-Terrain is a simple command line tool that will generate a mesh from DEM files either as TIN or TRN. The output can be saved as .obj file, so can be directly drag-and-dropped into meshlab. It will also support tiling with zoom levels in quantised mesh format.


5

If you use is the Delaunay triangulation from: Vector/Geometry Tool or in Processing/Toolbox QGIS:Delaunay triangulation, SAGA:Triangulate or GRASS GIS/v.delaunay All these algorithms perform a 2D Delaunay triangulation (only GRASS GIS allows a 3D Delaunay triangulation/interpolation but this command is not implemented in the Processing Toolbox) ...


4

There doesn't appear to be a GeoJSON spec out for TIN, but there is one for WKT. Basically, TIN is a synonym for MultiPolygon, and Triangle is a synonym for Polygon. Thus a four node, two element TIN can be encoded with the WKT: TIN Z (((0 0 0, 0 0 1, 0 1 0, 0 0 0)), ((0 0 0, 0 1 0, 1 1 0, 0 0 0))) Which should translate to: {"type":"TIN","coordinates":[[...


4

First you need to enable the extension (if you have the license for this): Create TIN (3D Analyst) http://resources.arcgis.com/en/help/main/10.2/index.html#//00q90000001v000000 You can search for this:


4

You could drape your geological polygons on the elevation surface you created to make them 3D. Two ways in 3D Analyst are Interpolate Shape and Add Surface Information. For an explanation of both see: http://resources.arcgis.com/en/help/main/10.1/index.html#//00q80000005m000000


4

You can't get elevation from Orthorectified photography. To get elevation data from airphotos you need special photos, hardware and software: Photos: Sterio pairs, a set of overlapping images with an accompanying file detailing the location of the aircraft at the time of capture (x,y and z). Hardware: 3d monitor, with glasses. Nowdays you can get cheap 3d ...


4

Per the help file: Hard and soft qualifiers for line and polygon feature types are used to indicate whether a distinct break in slope occurs on the surface at their location. A hard line is a distinct break in slope, while a soft line will be represented on the surface as a more gradual change in slope. See also this KB article, which provides ...


3

The link in Devdatta's comment partially addresses how to simply drape the vectors, but despite this you can still experience the issues the OP mentions. I believe (personal hypothesis) that the mismatch is due to the difference in triangulation between your vectors and the underlying TIN. You notice this especially with large polygons where the ...


3

Work with "Terrain" in ArcGIS instead of standard TIN. Then you will have the option of saving several "resolutions" and your rendering will be less of a problem. When zooming out, it will show a rough resolution, when zooming in, the resolution will increase. http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//005v00000002000000.htm.


3

You are looking for the in_memory workspace. Though the files are generally relased upon closure of the application, it's generally a good idea to remove it from memory by running Delete. If you are using this in a loop, you'll want to delete the temporary files before creating a new one with the same name. At any rate, it saves memory. For example: ...


3

The only way we found to get a triangular mesh with existing topology into ArcGIS was to use the arcpy.LandXMLToTin_3d function. It's a bit crazy to have to write out a LandXML file just to get your TIN into Arc, but it works. Here is a Python Toolbox for ArcGIS10.1 that accesses data on a triangular mesh from an ocean model, and brings it into ArcGIS as a ...


3

It is a fundamental issue. Each cell in a raster DEM represents a point height interpolated into a square.Between two raster cells there is thus a "vertical drop". A TIN however takes those height points and draws a slope between them. There is no "true" value for any location between the points, it is just two different ways of interpolating the known ...


3

The best recommendation I can give is don't. Creating a TIN using ArcObjects is a tedious process. You would be best looking at IGeoprocessor and calling the existing tools. If you have 5 points in memory then write them to a new shape file and create the TIN from points.


3

If you have access to the 3D Analyst extension, this can be accomplished using the TIN Node tool found here: 3D Analyst Tools - Conversion - From TIN - TIN Node. This will create 3D points (i.e Z-enabled) at each triangle node that forms the TIN. Alternatively you could convert your TIN to a raster, and then use the Raster to Multipoint tool which will ...


3

A solution is to generate random points and sample the elevation raster at each of these points, then interpolate these points with the method that you want (as in Ordinary Kriging Example: GRASS-R Bindings). If you use a script, there are many solutions 1) with R (many packages to do that) 2) with Python, one of the best scientific solution is Mayavi ...


3

I have not used Raster to TIN, but judging by the documentation (which has an image to demonstrate), the triangulation is not performed using all of the nodes in the raster. It uses only enough that the TIN elevation differences are within the Z tolerance. If you'd like a TIN that conforms more closely to the raster, reduce the tolerance.


3

You can use ST_Dump to extract individual TRIANGLE elements from the TIN. Then, you can convert an individual TRIANGLE to a POLYGON using ST_ExteriorRing and ST_MakePolygon. If you then need to combine these polygons into a single MULTIPOLYGON, you could use ST_Collect. Putting that all together would look like this: WITH test_geom AS (SELECT 'POLYGON (( ...


3

Probably the field type of ALT is not numeric. Interpolation plugin lists only numeric fields in the Interpolation attribute list. First check the field type in the layer properties dialog (right click on the layer name and properties from the menu and select fields tab). I suppose it is string. Use the field calculator to convert text data into a new ...


3

One way to achieve this is to run (Vector geometry tools/Delaunay triangulation) in QGIS. You can then delete the triangles that fall outside of your desired boundary. This will produce a shapefile which you can rasterize if that is the desired output. You can use any of the three fields to rasterize because each point is shared by multiple triangles (each ...


3

Be aware that .las and .obj are not the same type of data, in which the first is composed by points, and the second is a type of surface. So, even processing the point cloud to output a surface it is needed that the points in the .las file make sense to what is being generated. For example, triangulating first returns (for DSM) or last returns, or returns ...


2

Looking at the image, I'd say the breaklines have been added. You can see this in the triangulation and the blue breakline lines. However, you need to specify what the breaklines will do. I am guessing that your area represents some islands in a lake. In which case you may prefer to use hulls rather than hard breaklines (same dialog box, just a different ...


2

Also for this purpose at your service: SAGA GIS (has TIN module and a lot of tools for DEM analysis and manipulation) LandSerf (java-based, concentrated on DEM and TIN manipulation)


2

You can use the interpolation plug in. It is located in the raster menu.This is the dialog box The output file is a raster that you can use with the raster/analysis/dem (terrain models) to produce the slope (either degrees or percent) analysis. hope it helps


2

I have found personally that QGIS will crash when it runs out of memory. This happens when you're printing some big, raster heavy maps. So I reckon that's what is happening here. You could try some alternative methods. Some suggestions I have are: Use GDAL http://www.gdal.org/gdal_grid.html Try using GRASS via the QGIS plugin Get down and dirty with Python!...


2

Problem of the exporting was that I used local variables.. (Drag and drop from the same environment). And the problem of my script was that following the ArcgisHELP I also used local variables.. For scripting, when EDIT TIN, the full path with data source must be added, so insted just using variable, or local parameters: gp.EditTin_3d(raster, "...


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