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

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2
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2answers
84 views

Merging DEMs of different grid size

I'm trying to merge two grids with different cell size. One has a cell size of 10m and the other 50m. The 10m one covers a subarea of the 50m one. I know that the most accurate one is the 10m one and ...
1
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2answers
363 views

Elevation difference map using two DEM

I am studying glacier mass balance and have ASTER and SRTM DEMs. I want to make an elevation/volume change image such that it graphically represents changes in elevation difference in various parts of ...
0
votes
1answer
18 views

gdalbuildvrt error when mosaicking SRTM data with different NoData values

I'm attempting to mosaic together 9 SRTM tiles downloaded from CGIAR to produce a DEM of Borneo. I'm using: gdalbuildvrt Borneo.vrt BorneoSRTM/*.tif where BorneoSRTM contains the 9 tif files to be ...
3
votes
1answer
43 views

Very high resolution stereo-imagery

I'm looking for very high resolution stereo imagery to perform a DEM extraction. The only place I can find sample data is http://www.digitalglobe.com/product-samples but the form does not work for me. ...
0
votes
0answers
17 views

Digital Elevation Model Fusion

I want to fuse Digital elevation Models extracted from Carto-1 satellite. I already extracted DEMs & tried few algorithms in Matlab. Unfortunately as they are not Georeferenced i am not getting ...
0
votes
1answer
22 views

How to remove pixel values below 0 in Digital Elevation Model in ArcGIS?

I made a DEM layer from LAS file (LiDAR).Now for showing a map I have a map like the image below! I wonder how can I remove black area? They have the value -2 to 16! How is possible to set the value ...
0
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1answer
72 views

Viewshed calculation using SQL

Can i calculate viewshed in MS-SQL server? Viewshed analysis is Raster operation. I have elevation value vector observation as point vectors. Are there any methods to calculate Viewshed (using ...
7
votes
1answer
85 views

Account for bridge overpasses in a ground DEM to allow for water flow under the under the overpass

I have a bare earth DEM made from lidar data (A). It works well and has passed all accuracy tests. It is used in storm surge models. The problem we are having is on underpasses. I need to allow water ...
0
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1answer
40 views

QGIS 2.2: GDAL Grid (Interpolation) Error

As much as i understand Raster -> Analysis -> Raster (Interpolation) can provide me with a terrain file out of a shape file with a Z coordinate. I select the input and output file and a Z field. It ...
1
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0answers
47 views

How to get Drainage Divide and Streams from DTM

Does anyone know how you can get a map like this attached, having the digital terrain model? I'm sorry, but I do not know what is the exact technical term in English for them. I hope you understand ...
3
votes
1answer
40 views

Interpolate Temperature Using DEM

I want to "co-interpolate" temperature with DEM. I have SRTM 90m aggregated to 1km and I want to "co-interpolate" my DEM with points with temperature data. How do I do this? I am using ArcGIS 10.
1
vote
1answer
35 views

Find minimum elevation along a polyline and return xy or point?

Using ArcGIS 10.1 and Python IDLE 2.7.2... I'm trying to find the minimum value of a polyline with a raster layer and turn that LOCATION into a point. I put everything together in model builder, but ...
1
vote
1answer
141 views

Can I prevent QGIS raster clipper from changing output cell/pixel size?

I have performed a DEM extraction using the clipper tool in QGIS 1.9.0 Master, using a mask layer, the original resolution of the DEM is 20x20 but in the resultant DEM the new resolution is ...
2
votes
2answers
155 views

Driver Error : DTM to Raster using GDAL_GRID

I am looking to interpolate a DTM (eventually over 4,000 DTMs) that is in a personal geodatabase format. I would like to do this in as few step as possible, eventually writing a batch script to do ...
1
vote
0answers
27 views

How do I split a DEM at a certain elevation?

I have a DEM that includes bathymetry and terrain elevation and I would like to split it at the coastline. Ideally, I would end up with one tif that's land and one tif that's bathymetry. I have ...
1
vote
3answers
78 views

Calculate Number Of Pixels Visible From Pixel

I am looking for a way in which to take an input DEM and create an output raster whose pixel's value is the count of pixels "visible" from that location. I use ArcGIS with Spatial Analyst, but also ...
0
votes
0answers
17 views

DEM/DSM from contour lines and slopes

I want to create a DEM with as much detail as possible. The problem is, that the area contains several (manmade) slopes. I got contour lines and lines that mark the location of the slopes, but no ...
2
votes
0answers
30 views

When computing flow direction, the D8 algorithm is used - are there major differences if others are used?

I am a student working with Hydrological models. Within these models we can route water across a DEM (within a delineated watershed or just within an un-delineated DEM) using many different flow ...
3
votes
1answer
39 views

How to give elevation information to a polygon feature class using existing TIN file ? (geological mapping)

I'm an ArcGIS 10.1 user. My issue: I have a printed form of a map which depicts geological bodies being surface rock occurence. Additionaly, there are elevation contour lines. I digitized the map by ...
2
votes
1answer
42 views

Elevation maps from point clouds: TPS vs. what other methods

In the reply to another question, @thehealingprocess refers to "...a comparison of interpolation methods for interpolating elevation maps from LiDAR clouds, and in almost all scenarios thin ...
1
vote
0answers
32 views

What steps does SAGA GIS take when calculating Topographic Wetness, specifically when handling depression filled (by ArcMap) DEM

I am a grad student involved with hydrological modeling. In the model I work on, we are calculating the Topographic Index (TI; without transmissivity - or set to 1) using Quinn's MFD algorithm. We do ...
6
votes
4answers
345 views

How to extract breaklines from a given DEM?

Breaklines are very useful for describing a terrain - for example to build an exact TIN. My question is, how to extract these breaklines from a given DEM? I calculated the curvature (vertical) - ...
2
votes
1answer
103 views

qgis2 slope analysis from NED data gives crazy histogram

I'm attempting a simple slope analysis in QGIS2 using the plugin at Raster -> Terrain Analysis -> Slope. The slope output layer has a very strange histogram, basically spikes at 0 and at 89.9098 with ...
1
vote
1answer
40 views

QGIS DEM (Terrain models) Mode Slope creates wrong data [duplicate]

I have a DEM raster file downloaded from the USGS site. The file can be downloaded here. I am trying to create a slope raster in percent with the DEM tool in QGIS. The GDAL command is the following: ...
3
votes
2answers
188 views

How to create 3D water depth with ArcScene?

I was trying to visualize flood depth in 3D using ArcScene. What I had for this purposes are: high-resolution DTM of the valley orthophoto and Raster with flood depth information. I have draped ...
4
votes
2answers
542 views

How to drape a simple jpeg image over dem of some area?

How can we drape a simple jpeg image which doesnot have any geo referencing information over the digital elevation model in order to visualize it in 3D in QGIS?
1
vote
1answer
175 views

Polyline ZM: automatic vertex height errors correction

Paolo I've got many rivers (polylines ZM) with a lot of height errors in Polylines 'vertices. Vertices' Z errors are not all equal in height (i.e. they are not all at zero height). I must create a TIN ...
1
vote
1answer
48 views

Fill sinks error in arcHydro

I am working on a project that is modeling runoff at a county level. The DEM used is lidar derived and has a 5 ft resolution. The general workflow I am flowing is Sink evaluation Sink Selection (to ...
6
votes
2answers
721 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 ...
-1
votes
0answers
22 views

Slope function in ArcMap gives weird outputs [duplicate]

I try using the slope function to calculate the slopes of my ASTERDEM. The output contains only three value ranges: 0, 89.59-89.99, 90. I tried redefining the project system, but it still gives weird ...
1
vote
2answers
56 views

What are the ways we can control the quality of a DTM?

I imagine that for DTM obtained from Stereoscopic procedures or interpolation from a set of topographic points a comparaison with the original data can help, but what for DTM obtained from Remote ...
3
votes
2answers
130 views

Creating DSM and DTM from a LAS using a freeware solution

Is it possible to export a surface and terrain model files from an aerial, LiDAR point cloud (LAS) set? I am using SAGA GIS for very basic operations, but I couldn't find this option (and I have a ...
1
vote
1answer
50 views

Where can I obtain 3D data for Singapore?

I am looking for providers of 3D maps/models of Singapore. This might be either from photogrammetry/laser techniques or based on a DEM + building footprints/landuse with a height attribute. Is any ...
2
votes
0answers
31 views

Define uphill side of roads and buildings

I have a big raster of a mountain region and I need to extract the uphill side of roads and buildings, from these elements to the pick of mountains. For a road I know the uphill side changes in ...
11
votes
5answers
6k 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 ...
0
votes
1answer
31 views

How determine data type of points in geotiff DTM?

I have some DTMs in geotiff files. I need to read them in C# and I've decided to use libtiff for that purpose. After some investigations, I've found that there are tiled tiffs, so I use ReadTile ...
4
votes
2answers
292 views

Focal statistics to calculate saddle points from DEM

I have a conundrum with Focal Statistics and kernel files. I am been trying to identify saddle points in DEMs. I am attempting to rewrite this (thanks whuber) in a python script for 10.1. I have ...
0
votes
1answer
39 views

DEM difference looks like a hillshade

I wanted to find the elevation difference between 2 DEMs. When I got the data, I had to georef one image and had to aggregated it too because their cell values do not match. I also tried to resample ...
0
votes
0answers
82 views

converting vectors to raster (burning streams)

I converted my stream vector to a raster file (using polyline to raster conversion tool). I anticipated that I would get a No Data row in the raster file attribute table, so that I could use a ...
4
votes
5answers
651 views

Calculating Runoff / Streams using DEM in ArcGIS

I am just curious about the workflow that many of you use for runoff/stream analysis using a DEM and create a "water network" from the results in ArcGIS 10.1? I know the average rainfall for different ...
0
votes
0answers
27 views

r.shaded.relief plugin on a DEM layer

I loaded a raster digital elevation map from the DEM explorer website. I defined the projection and created a mapset. I then loaded the raster file into GRASS with the r.in.gdal plugin to create a DEM ...
0
votes
0answers
17 views

Adding a Z Unit [duplicate]

I'm struggling with the Z Unit conversion of some data. Both the NHD data and my DEM are in a GCS with Decimal Degrees. These data sets project perfectly on the fly, but after I adjust the Z Unit of ...
0
votes
1answer
42 views

Adjusting Z Units on a DEM

I am learning how to use ArcHydro and attempting to change the Z Units because I get a warning message saying the Spatial Reference Doesn't Match. The DEM was in Meters, and I adjusted the Z Unit to ...
4
votes
2answers
207 views

how do you identify ridges on an elevation raster?

I was wondering whether anyone might be able to tell me in layman's terms how to extract or differentiate between ridges and hilltops from 10m elevation data using ArcGIS 10.1? Any advice would be ...
5
votes
7answers
387 views

Open source tool to convert a DEM to a 3D model

I would like to convert a DEM (Digitial Elevation Model) file (e.g. from SRTM) into a 3D model that I can then edit with regular 3D modeling tools (e.g. Meshlab/Blender/etc.). However I'm using Ubuntu ...
0
votes
0answers
46 views

Creation of drainage ditch in ArcGIS - Line with a certain slope

I have a digital terrain model and a list of problematic points, in which water accumulates. It's not important how I obtained these points (by observing or some algorythm). I would like to use these ...
2
votes
2answers
109 views

Create Contours From a DEM without 3D or Spatial Analyst

I'm wondering if there is a way to create contours from a DEM using ArcGIS without 3D or Spatial Analyst Extensions. I know that there are a few questions out there pertaining to this (How to create ...
2
votes
2answers
82 views

How to produce a CSV file from .tif file with elevation data? [duplicate]

just want to ask, I have a .tif file that contains all the elevation of a country. How can I convert that to a CSV file that contains x,y,z values where x and y are the latitude longitude respectively ...
4
votes
1answer
60 views

What are the most efficient Geographic Weighted Regression packages?

What are the most memory efficient open source packages for calculating a geographically weighted regression (GWR)? I am in a situation where I need to do a geographically weighted regression on a ...
4
votes
2answers
154 views

How to de-noise a DSM

I have created a DEM, DSM, and nDSM from a LiDAR Point Cloud using SAGA-GIS. I extracted the appropriate returns from the point cloud, then converted to grid, and then closed gaps to fill in any ...