Digital Elevation Model (DEM), which could be a Digital Terrain Model (DTM) or a Digital Surface Model (DSM).
2
votes
2answers
2k views
Viewing .las format LIDAR data in QGIS?
Is there an easy path to visualizing this LIDAR data? I have QGIS, and some USGS LIDAR data in (.las) format downloaded from http://lidar.cr.usgs.gov/ . This means I have both the (.las) and ...
4
votes
2answers
411 views
comparing two TINs
i have the following two files:
1) LiDAR las file1
2) 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 ...
6
votes
1answer
249 views
Problems creating TIN from British Columbia DEM data
Is anyone familiar with creating a TIN using ArcGIS9.3 and British Columbia DEM data (.GEN files)?
I can't figure out how to get the breaklines to work during the creation of the TIN. Using ...
2
votes
3answers
919 views
How to convert raster data into regularly sampled points?
I am wondering if there's another way to convert raster data (ex: DEM) into regularly sampled points. I've used Raster to Point under ArcToolbox previously, but if the raster data is huge, that's a ...
4
votes
2answers
852 views
How to use NASA Digital Elevation model data?
I've heard it is possible to use NASA elevation model to determine approximate elevation at (lat;lng) point.
This might be really useful for my upcoming project since Google Elevation API has weird ...
7
votes
4answers
3k views
Is it possible to make a DEM from contours in QGIS?
Is it possible to make a DEM from contours in QGIS? I have a shp file (contours) and their heights, can I use QGIS for produce a DEM without using GRASS? I find this creating a dem from contours but ...
5
votes
2answers
883 views
How to build an artificial 'dam' across a river?
I have a DEM.
Created all files related to watershed including accumulation, direction, streams etc...
I'm stuck creating a dam.
I request you to please let me know how to build an artificial 'dam' ...
2
votes
2answers
989 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
4answers
2k 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 ...
13
votes
1answer
710 views
Good practice for generating contours from a DEM
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: ...
6
votes
1answer
485 views
FOSS method to split raster into smaller chunks
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 ...
4
votes
1answer
370 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 ...
11
votes
3answers
611 views
Detrending DEMs? - Removing the elevation trend over sloped surfaces (diagram included)
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). ...
6
votes
3answers
733 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 ...
17
votes
3answers
2k views
How to smooth a DEM?
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 becouse the area is near flat and the DEM is 90m in ...
0
votes
2answers
902 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
380 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 ...
4
votes
1answer
347 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 ...
5
votes
1answer
5k views
creating a dem from contours
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 ...
8
votes
4answers
1k 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 ...
2
votes
1answer
625 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
489 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
1answer
290 views
When merging two DEMs, do they have to be in the same pixel bits?
I have a simple question. 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 ...
2
votes
1answer
522 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'm trying to do this many times using spatial analysis-solar radiation calculation tool in arcgis. ...
9
votes
4answers
753 views
Are there any open source tools to detect and fill sinks on a DEM?
Are there any open source or inexpensive tools to detect and fill sinks on a DEM? ESRI Spatial Analyst is just out of my price range.
4
votes
2answers
713 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
329 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 ...
1
vote
1answer
209 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: ...
4
votes
2answers
529 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
602 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
291 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
510 views
Interpolation: irregular shape, merging DEM's
my problem is quite complex, though 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 ...
5
votes
1answer
4k 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 ...
4
votes
3answers
288 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 ...
7
votes
1answer
541 views
Partially update a raster (a DEM)
My todays question is: 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 ...
6
votes
6answers
535 views
How can I convert a DEM into areas of “flatness”, with an arbitrary fill/cut to area ratio?
I want to find areas of relative "flatness" in a DEM.
How can I find flat areas? I want to find a neighbourhood of contiguous cells that have an elevation variance that is within a certain ...
3
votes
1answer
358 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 ...
10
votes
2answers
810 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 ...
11
votes
4answers
2k 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 ...
4
votes
2answers
10k 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
1k 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
485 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 ...
1
vote
3answers
1k views
Where can I download 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 ...
5
votes
1answer
1k 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 ...
