Questions tagged [dem]

For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)

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2
votes
2answers
3k views

Converting ASCII grid/NTF to SRTM/DEM

I want to use the Ordnance Survey Land-Form Panorama product in some software called Maperitive, which can read custom SRTM DEM files. The data is provided in the following formats: DXF [Contours] ...
3
votes
5answers
8k views

Can I convert ESRI Grid (DEM) raster to USGS DEM?

There is a tool for DEM to Raster in ArcGIS but I need to convert my ArcGIS DEM rasters (mostly LiDAR) into USGS DEM. The idea is to import this DEM into Sketchup and create a "sandbox" TIN surface ...
16
votes
3answers
4k views

Generating contours from DEM using GDAL?

We have just received a large set of DEMs at work and I would like to generate contours from them. The DEMs have a resolution of 1m and a size of 1kmx1km. Output from gdalinfo: Driver: AAIGrid/Arc/...
17
votes
5answers
12k views

Using SRTM Global DEM for Slope calculation?

I have downloaded SRTM GDEM (~90 km resolution). I am using ArcGIS 10. I have tried to use spatial analyst to compute for slope. However, I can not compute for the slope. The output values has ...
18
votes
5answers
7k views

Splitting raster into smaller chunks using GDAL?

I have a raster (USGS DEM actually) and I need to split it up into smaller chunks like the image below shows. That was accomplished in ArcGIS 10.0 using the Split Raster tool. I would like a FOSS ...
5
votes
1answer
1k views

Obtaining a contour as a single polygon in ArcGIS?

I have a DEM that I want to retrieve a single contour polygon from at a given elevation. I can use the Contour tool to obtain a series of polylines at a given elevation by setting the contour interval ...
6
votes
3answers
3k views

Finding elevation differences between adjacent pixels in ArcGIS Desktop?

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 ...
7
votes
5answers
15k views

Converting LiDAR data to raster (DEM/DSM) for ArcGIS input?

I was wondering if there is an option to convert LiDAR data (.las) to a raster/grid (DEM/DSM) format that ArcGIS 10.0 can read?
44
votes
5answers
18k views

Smoothing DEM using GRASS?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough because the area is near flat and the DEM is 90m in ...
5
votes
1answer
513 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 ...
2
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1answer
1k 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 ....
16
votes
3answers
4k views

Removing elevation trend over sloped surfaces?

Is there a known methodology for removing the trend from a DEM surface? For example, if I had a DEM of a river, that river would flow from high elevation (upstream) to lower elevations (downstream). ...
3
votes
0answers
1k views

Is it possible to reverse the trend/values of a raster?

For example - if I have a raster DEM covering a stream with higher elevations in the west (up river) and lower elevations in the east (down river) is it possible to reverse this trend so that the east ...
8
votes
5answers
1k views

Calculating total ascent along path? [closed]

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 ...
11
votes
2answers
46k views

Creating DEM from contours using ArcGIS Desktop?

I have a large set of contours that I received broken down into several different subsets. I have merged most of the subsets together creating a larger set of contours in three different files. I have ...
9
votes
5answers
5k views

How to aquire a topographical map of Britain?

First of all, let me say that I know next to nothing about GISs. I'm trying to find / make / aquire a topographical map of britain. I want to use it as a height map in Dwarf Fortress so it needs to ...
5
votes
1answer
420 views

Merging two DEMs in different pixel bits?

I have 2 different Digital Elevation Modeling (DEM). One is the state DEM and has 30m and has 16 pixel bit. I have a couple of smaller DEM that has 30m but they have 32 pixel bit. I know how to merge ...
2
votes
1answer
3k views

Converting 32 bit DEM to 16 bit in ArcGIS Desktop?

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 -3....
2
votes
1answer
695 views

Importing ERDAS-processed GTOP030 dem data into ArcGIS Desktop?

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 ...
3
votes
1answer
1k views

Solar radiation calculation from GTOP030 DEM image

Can you help me to calculate solar radiation from GTOPO30 DEM image at the 30 m spatial resolution. I've tried to do this many times using spatial analysis solar radiation calculation tool in ArcGIS....
5
votes
2answers
2k 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. ...
3
votes
1answer
2k views

Determining if DEM has z values?

How do I know if the DEM contains z-values? I am looking at the DEM's layer properties and it does not mention the z values. I then add it to ArcScene and tried to find it without success. It ...
3
votes
1answer
711 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: ...
10
votes
2answers
1k 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
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2answers
1k 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 ...
9
votes
3answers
5k views

Workflow for determining stream gradient?

As far as data goes, I'm working with NHD .shp files, 10m DEMs, and some LIDAR data. My goal is to determine gradient for 100m segments of a network of streams. I'm already able to do this, but I ...
2
votes
1answer
901 views

Combining DEM raster with vector data in ArcScene?

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 ...
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
554 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 ...
6
votes
1answer
6k 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
4answers
4k 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 ...
9
votes
7answers
4k views

Is there an online tile-based elevation service?

I am working on an application that requires the elevation at a given lat/long coordinate for lots of closely spaced coordinates along any given irregular path. (The path is a trace of a glider/hang-...
6
votes
3answers
1k 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 ...
100
votes
6answers
155k views

Differences between DEM, DSM and DTM?

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately: DEM: Digital Elevation Model DSM: Digital Surface Model DTM: Digital ...
5
votes
2answers
1k views

Comparing two TINs created using ArcGIS for Desktop?

I have the following two files: LiDAR las file1 Let's give it a name LiDAR las file2, contains the same file1 data, where number of points randomly removed. So if file1 contains X number of points, ...
8
votes
1answer
2k views

Partially updating raster (DEM)?

How to update an .img DEM in ArcView 9.3? I do have DEM which need to be updated only if few parts. The area to be updated has been produced in separate DEM with Spline Interpolation with Barriers. ...
6
votes
1answer
858 views

Interpolation: irregular shape, merging DEM's

My problem is quite complex, but I hope that solution may be simple or at least possible. I do have .img DEM 0.5x0.5m. DEM consists of river bed, river valley and adjacent areas (it is strip of 5km ...
4
votes
1answer
887 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
341 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 ...
11
votes
2answers
2k 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 ...
6
votes
2answers
39k views

Merging several DEMs into one using ArcGIS Desktop?

Is there any ArcGIS 10 tool to merge several DEM into a single one?
17
votes
4answers
6k 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 mountains,...
0
votes
0answers
749 views

How to calculate buildings shadow areas

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 ...
13
votes
2answers
2k views

What is the smallest contour interval possible when derived from a DTM?

I am converting a 2m DTM to contours, and would like to have the smallest interval possible. Is there a theoretical limit, or even a rule of thumb for defining contour intervals based on the ...
4
votes
6answers
4k views

shadow simulation from buildings [duplicate]

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?
12
votes
4answers
5k views

Comparing two Digital Elevation Models (DEMs) from LAS files?

I have two LiDAR files (.las), one is original let's say with X points. And the other is copy of the first .las file but with Y points, where Y is less than X. Now, I want to compare the Digital ...
5
votes
1answer
3k views

USGS DEM Easting and Northing metric and unit

I have to do some programming work with DEM files. I got some DEM files from http://geobase.ca/geobase/en/find.do?produit=cded the 1:50,000 version and read in the data. According to the DEM ...
16
votes
9answers
38k views

Converting XYZ files (with regularly spaced xy) to ESRI GRID format?

Normally consultants (LiDAR survey) provide me with data to my specifications; already in ESRI GRID or ASCII GRID format. This way LiDAR data can be easily used with ArcGIS. This time I only have xyz ...
16
votes
4answers
8k views

Calculating elevation profile along line from a DEM?

Given a DEM (Digital Elevation Model) and a line (x1,y1) --> (x2,y2) (paired coordinates (x,y)), how can one calculate the elevation profile or cross-section projected on that line? I am looking for ...
2
votes
3answers
3k views

Downloading 1 arc-second elevation data for Canada other than Geobase?

Can someone suggest a source for Canadian elevation data better or equivalent to 1 arc-second? I have a good data source for Ontario but for other provinces folks often recommend Geobase which claims ...