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Questions tagged [dem]

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

Digital Elevation Model (DEM). Terms with overlapping meaning include Digital Surface Model (DSM) and Digital Terrain Model (DTM). DSM is generally a surface model, DTM is generally a bare earth model. DEM could refer to either.

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2027 questions
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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 specifications, there is a quote: "... a 4x2 array…
Jake
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Creating DEM from mesh?

I have a mesh ( with points and triangles that define it), and I will need to create a DEM model out of it ( in geotiff format if possible for space consideration, if not, then in ASCII grid format). I need the DEM for watershed and catchment…
Graviton
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DTM posting and resolution

When speaking about a DMS or a DTM, what is posting? And what is the difference between posting and horizontal resolution?
user3911093
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DEM sources for arctic regions

Are there any 90m DEMs out there for regions north of where the SRTM dataset ends? I looked at ASTER, but it seems to have a lot of unfilled voids, and it's important that the resolution matches the datasets I already have.
Erin
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Difference between ALOS median and average DEM version?

Downloading DEM from ALOS gives you a Median and an Average version. Which one is to be used for which purpose? In my case, I want to produce an R-Index map using QGis (Slope & Aspect algorithm + some Raster Calculation).
dadadingo
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Should only a "bare-earth" DEM be used when calculating CTI?

I have 50-meter DTM and 20-meter DSM data available to choose from to use for calculating a compound topographic index (CTI). While the 20-meter resolution is more attractive, logic tells me that when calculating the compound topographic index…
fbiles
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Creating Data Elevation Model from two sources

I have 2 Data Elevation Models ( Aster with 30 m resolution and a DEM obtained by stereo with 4 m resolution ). Unfortunatly the DEM with high resolution contains a lot of no data value and some values with low accuracy. So, I want to use the two…
Mohamed wassim Baba
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Simulate sun movement

Are there any software packages/solutions that allow me to simulate the movement of sun or direction of sunlight over a period of time (e.g. 24 hours)? My purpose is to determine the regions cast in shadow for different times of day, when used in…
Corse
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how to extract elevation data using a DEM

I have digitized an LULC layer from satellite imagery, now I want to extract the elevation data from it. I have obtained DEM images from SRTM amd ASTER. How do I proceed?
Tsangpo
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How do I reduce contour intervals (i.e. from 50m contours to 10m contours) without using DEM?

I have shapefiles (lines) of contours having 50m intervals. How can I reduce the intervals to 10m without first converting the 50m contours to DEM?
Kingsley Severine Fitz-Gerald
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DEM data - Central Europe - noise in heights

I have downloaded DEM data from this page: http://www.viewfinderpanoramas.org/dem3.html. I have written simple program in C++ that takes "bricks" and build resulting height map. Hovewer, I have problem with result. I am using Mercator projection…
Martin Perry
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How view or query this DEM dataset

All I want to do is get accurate elevation data, so that I can compare short but very steep hills to pedal up on bicycle. I start here and see this 2018 DEM: Lidar-Topo 2018 PA Luzerne County Lidar Point Spacing: 0.35 m Alternate Name: USGS:…
Bob White
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Infer the topobathymetric surface of a reservoir

I have a DEM that just represents the water surface of a reservoir, and I would like to infer its depth geometrically, as shown below: ideally i would like to get a 3d line of this reservoir bottom, just like that: Does anyone know of a tool…
Vinicius B. de S. Moreira
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ZVI Analysis Tool - unexpected results

I have run the ZVI analysis tool from the perspective of an observer standing on a hill looking out to a defined altitude. However, the results do not correspond to my expectation from the underlying terrain data (black dot is the location of the…
Sam
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Issues Converting DEM to a Lower Resolution in QGIS 3

I am having issues converting a 1 m DEM to a 5 m DEM on QGIS. I am working in the NAD83 UTM 20 projection and whenever I convert my 1 m DEM to 5 m DEM the output is always less than 5 (often 4.9987 or something like that). My thoughts were that this…
Erioderma
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