Questions tagged [dem]

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

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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
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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
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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
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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
9k 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 ...
4
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5answers
4k views

Merging DEMs or other raster datasets and clipping Raster dataset to vector line?

I have two DEMs that I am going create a hillshade from, and ultimately want one hillshade clipped to a county boundary. I am running into a couple problems, though. When I try to merge the two ...
7
votes
6answers
2k views

Converting DEM into areas of “flatness”, with arbitrary fill/cut to area ratio? [closed]

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 ...
11
votes
5answers
3k views

Are there any open source tools to detect and fill sinks on a DEM? [closed]

Are there any open source or inexpensive tools to detect and fill sinks on a DEM? ArcGIS Spatial Analyst is just out of my price range.