Digital Elevation Model (DEM), which could be a Digital Terrain Model (DTM) or a Digital Surface Model (DSM).

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6
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3answers
1k views

How to find the elevation differences between adjacent pixels in ArcGIS?

Is there a way to determine what the difference in elevation is between two adjacent pixels? I am using an SRTM DEM to map faults. I am using the vertical error (>16m) as a criterion for the ...
5
votes
1answer
373 views

How to find upstream - lateral and downstream zones around urban areas?

I've a DTM and a shapefile of built-up areas. For a fire risk model, I've to find (within a defined buffer zone) two zones around built-up areas: one that is above/higher and lateral and the other ...
1
vote
2answers
2k views

DEM problem in ArcGIS

I have a 32 bit DEM with resolution 0.5 * 0.5 and range of elevation is 1299 to 1489. When I want to export or use copy raster tool or create fill in Arcgis, the results are elevation between ...
2
votes
1answer
639 views

Read .DEM (USGS) FIles with C#

I have a huge number of .DEMs and have been investigating how to process them into something useful. Does anyone know how, or even if it is possible to read coordinates and elevation data from ...
8
votes
5answers
723 views

How to calculate the total ascent along a path

I am working on a series of footpath routes and have been asked if it possible to calculate the total ascent that a walker would have climbed if the travelled along each route? I know that it is ...
4
votes
1answer
1k views

How do I know if the DEM has z values?

How do I know if the DEM contains z-values ? By looking at the DEM's layer properties and it does not mention the z values. I then add it to the ArcScene and tried to find it..nothing... It only ...
2
votes
1answer
715 views

Combine DEM raster with vector data. in ArcScene 9.3

Ive have a raster layer of earthquake data that includes depth. I also have a DEM file. The problem is that I need to plot earthquake depth relative to the DEM file rather than sealevel in order to ...
4
votes
2answers
1k views

Translating grid to USGS .dem in C# via GDAL

I am attempting to translate ArcInfo binary grids to USGS DEM format (.dem). I have installed the GDAL .NET bindings thru this build installer. I can get to GDAL in my C# add-in I am working on. ...
1
vote
1answer
479 views

Importing ERDAS-processed GTOP030 dem data into ARCGIS

I have two GTOP030 DEM images. After downloading them, I have imported into ERDAS and mosaiced them. Then I have exported it to .tif file in order to open it in ARCGIS. But when I tried to open it in ...
2
votes
1answer
359 views

Command r.sunmask in GRASS

I have hypsometric model of relief, and I need to visualize shadows. I was suggested to use GRASS command r.sunmask, so I tried to set time values and run command, but it gives me an error "ERROR: ...
8
votes
2answers
641 views

Elevation profile sample point algorithm

In generating an elevation profile, samples from the underlying raster must be taken. If the objective is to create a profile of maximum quality, how should the locations of sample points be ...
6
votes
2answers
745 views

What's a good toolchain to reproject some PNGs in plate carre to UTM?

I have some PNGs produced from Canadian DEM data. They're 1201px by 1201px heightmaps. Each one represents one quarter of a degree latitude and one quarter of a degree longitude. But I want to work ...
5
votes
3answers
1k views

getting from a DEM to points that could be used for a TIN

I have a DEM, and would like to create a set of points that I can use to make a mesh for a 3d modeling program, such as Maya, Blender, or SketchUp. If I were to make a TIN from a DEM in ArcGIS, ArcGIS ...
0
votes
1answer
413 views

How to transform a DEM to a cartesian coordinate system?

I am using the script r.inund.fluv. I run the script with all the required parameters and it produced a lot or errors. I emailed the author of the script and he said that "I think you are not ...
5
votes
1answer
5k views

Watershed Delineation

I am trying to delineate just the catchment area of some lakes, and am wondering the correct way to do this. I already have a filled DEM, along with a flow direction and a flow accumulation raster. Is ...
3
votes
3answers
2k views

River drainage basin boundary

I'm looking for a set of outlines of the river basins in the UK - I don't need a particularly detailed or highly accurate map - just a map saying point X will drain into the Thames or point Y will ...
5
votes
3answers
470 views

Is there a DTM available for free somewhere?

To go a little bit further than the semantic question regarding DEM/DTM/DSM, I'd like to know if there is a free (of charges and use) DTM datasets? And what about resolution? As far as I know,only ...
3
votes
1answer
570 views

Where can I find USGS SRTM 3 index grid or what procedure should I employ to select tiles?

I would like to download all USGS SRTM 3 tiles for Ontario, Canada from the USGS site: http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/North_America/ Where can I obtain the index that will assist me in ...
4
votes
1answer
282 views

Extra lines in Sketchup DTM when using stamp tool

I have a DTM in Sketchup. I am trying to use the stamp tool to make a level area on which to build a building. However, when I use the stamp tool lots of extra lines appear on the DTM seemingly at ...
10
votes
2answers
1k views

Surface distance on DEM between two coordinates

Given two coordinates on a digital elevation model (DEM), how do I compute the actual distance traveled between the two locations, assuming a straight line route? How will changing the resolution of ...
13
votes
4answers
4k views

Shaded relief from DEM in GRASS and QGIS

I have been trying to get a good looking shaded relief model out of GRASS and Qgis for a day or so now and just can't seem to get it. The biggest problem I'm having is the valleys look like ...
5
votes
2answers
21k views

Merge several DEM into one in ArcGIS 10

Is there any ArcGIS 10 tool to merge several DEM into a single one?
3
votes
6answers
2k views

shadow simulation from buildings

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?
0
votes
0answers
620 views

buildings shadow areas calculation

is it possible to calculate shadow areas of buildings or simulate shadows of buildings in a city using e-cognition software, with the DSM of the buildings and the sun angle and azimuth known?....if ...
5
votes
1answer
2k views

USGS DEM Easting and Northing metric and unit

Greetings to all! First post in here. Firstly, I am a complete noob in geography. But I have to do some programming work with DEM files. I got some DEM files from ...