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

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9 views

Is there a way to Alter Elevation Values of Pixles of a DEM based on BM and Control point elevation from actual Field survey?

We have got a quick bird DEM of our site. After getting actual on ground elevation values with a differential GPS device, we have found that there is a difference of average 12 feet between DEM and ...
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6 views

Resampling and snapping DEM to match a second raster

I have a DEM that is derived from a 50K map (provided by Geobase Canada), the resolution indicates it is 23.19156058m per cell (raster name DEM_50K). I need to resample this DEM to a 100m cell size ...
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1answer
18 views

Dtm format save only heights

I need dtm format that store only heights and scaling and left up position for saving storage I glad to know if any stadard save heights that way
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70 views

Tree counting using LiDAR data

Does anyone have any ideas on tree counting using lidar point data? I have a small set of lidar point data (plantation area about 500 hectares), from which I want to collect number of trees per ...
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25 views

Errors on TIN from contours distributions [closed]

I created a TIN from contours and it has errors like: Areas which suppose to be represented as 380 is on 40 meter interval and some which are mountain peaks have lower values. A snapshot is below. ...
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2answers
21 views

Equidistance on line contour from DEM

I am using a SRTM 30 meters for slope and elevation. When i'm using this 30x30 rasters to generate contours i set a 30m equidistance for contour, and the results are ok. Now i'm wondering if it's ...
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16 views

Whitebox GAT not starting under Windows 10 - General JAVA or Whitebox problem?

I am currently running the DEM preprocessing on a relatively large (50000 km2 at 30 m resolution) and steep DEM. The objective is to extract the stream network and some morphologic attributes (e.g., ...
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2answers
37 views

Update raster pixels on a DEM

I have a DEM in the form of a raster that I would like to update in certain locations. Ideally, I'd like to be able to create a separate polygon or point shapefile with the values, in the correct ...
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1answer
12 views

In QGIS, add to existing dem tiles and expand corresponding contour coverage within a project

In my first QGIS project I have dozens of digitized layers that have spread beyond the contour and dem tile area that I started with. Please recommend how to safely expand or replace the dem and ...
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6 views

Apply mask on ERDAS LPS

I am currently working on my final year dissertation and most of it is done on LPS. I am using Cartosat-1 and ALOS PRISM imagery to create DTMs for an area that is located on a peninsula. The problem ...
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25 views

Combining multiple DEMs into one file geodatabase

I have multiple file geodatabases (approximately 240) each contain a DEM. My issue is taking the DEM from each and putting it into a single file geodatabase without alot of mind numbing work. ...
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13 views

how to define threshold value in r.stream.extract

I want to generate streams using r.stream.extract. on what basis we have to define the threshold value. I am using aster dem with 30m posting.Also i want to know the minimum stream length to be ...
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24 views

Quantifying amount of sunlight falling in a region

I am trying to objectively quantify or provide some form of indication that could point toward the amount of sunlight Anyone knows if there are any datasets (either instrumental or remotely sensed ...
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44 views

How to run a tool from Whitebox GAT in ArcGIS?

I have a series of tools that I need to run in ArcGIS to hydrologically condition my DEM, but the first step in this process is running the Breach Depressions tool from Whitebox GAT (I have found that ...
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12 views

Extracting Elevation (DEM) from air photos using open source software? [duplicate]

I have a few pairs of stereo air photos and I want to extract a DEM from them. I think that is possible using PCI (OrthoEngine), but I would like to do it using Open Source (or at least free) ...
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31 views

High Resolution Terrain Data for the Philippines

Where can i download Philippines terrain data that is better than the 30 m ASTER global dataset?
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66 views

How to extract elevation from a DTM?

I'm using ArcGIS 10.1 I'm working on a project for landslide by using ModelBUilder. One of the data I used is DTM for the area elevation. The problem is I don't know how to extract the elevation out ...
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2answers
36 views

Topographical Elevations for Central Africa and Cameroon

I am using QGIS and I have been faced with the problem of topographical maps. From searching online I could only find data for the United States. Google maps offers elevation contours, however I am ...
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16 views

Is there an existing tool or plugin to automate the elevation versus volume relationship of a dem within a user provided polygon

I often need to obtain the elevation versus volume data for a proposed basin site but have not found a truly automated solution. I would simply like to create a bounding contour polygon of the DEM ...
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2answers
182 views

Masking out places with elevation below 5 m from a DEM

I have a DEM of a study region; I want to modify the DEM in order to reflect the coastline outlook when the sea level was 5 meters higher than today. What I have done so far is to use 'Raster ...
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20 views

ASTER data error causing “bumps” in elevation

I am working in ArcScene (10.1) with some 30m resolution ASTER data from Indonesia, and am getting anomalous "bumps" in elevation in my study area. In google earth it is not there, and I know from ...
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1answer
34 views

Simplify / generalization of flow lines

I'm trying to make a model of surface runoff of rain water. I'm using GRASS GIS function r.flow, which generates nice smooth lines of runoff. What I need is edit these flowlines someway to avoid ...
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26 views

Z factor to get the results in square meters and cubic meters?

I have a DEM surface in WGS 1984.I want to calculate surface area and volume in different elevations.I wonder for example If I want to measure the area and volume below some height how shall I set the ...
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1answer
37 views

Determining length of roads that fall under low elevation using ArcGIS Desktop?

I am working on a project on sea level rise impacts of roads. Basically I need to determine length of roads that fall under low elevation (from 1m to 5 m elevation). I have a DEM file and road shape ...
2
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1answer
36 views

Calculating slope for points with downhill slopes rendered as negatives in ArcGIS

I have a DEM and a series of points. I'd like to measure the change in slope along the series of points. Distinguishing between uphill and downhill slopes matter to me, and ArcGIS' slope function ...
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1answer
71 views

SAGA tool 'Relative Heights and Slope Positions' - What do results tell me?

I am currently trying to get in morphometry, using the SRTM 30m DEM. I was recommended to test the SAGA mudule 'Relative Heights and Slope Positions' ...
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20 views

line from min to max of a digital elevation model

I have some geometries as multipolygons and a dem (digital elevation model). I need a line from the max value to the lowest value of the dem for every multipolygon. Is qgis a tool i could use or do i ...
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1answer
45 views

How to extract points from a Digital Elevation Model in ArcGIS 10.1?

More specifically my question would be if there is a way to create a grid over the digital elevation model in GIS and extract points, or elevational data, from the intersecting points of the grid? I ...
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22 views

Calculating slope from elevation returns hole when using ST_Slope in PostGIS

I have rasters from the National Elevation Dataset loaded into a PostGRES database and am using the built-in function ST_Slope to calculate the slope. However these contain many holes where there is ...
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32 views

How to remove las2dem streaks from raster dem

I've created a series of DEM files using the las2dem tool from LAStools, however since I don't have a licensed version they have black streaks running across them. Does anyone know a good method for ...
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14 views

Another Z-Factor Challenge

I've been working on a DEM, trying to calculate the slope. I have it in WGS_1984 and re-projected into NAD_1983_MTM_8, my preferred projection for this project. Every time I run the slope tool, ...
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1answer
43 views

ArcGIS Raster To Multipoint Mac/OSX alternative

Is there an alternative to the ArcGIS Raster To Multipoint tool for Macs? The VIP thinning method is particularly of use. A comparative point cloud thinning/simplification tool to this would just as ...
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1answer
57 views

Getting aspect and reclassifying raster files using Python in a loop

By using Python in PythonWin 2.7.3, I tried to obtain aspect files of a list of raster files in a folder(called database_Dem20) and save it to another folder, database_Dem20/testOutput. In the same ...
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36 views

How to interpolate a Raster DTM

I have a GeoTIFF DTM produced from Agisoft Photoscan at 0.05 m resolution. However the interpolation used by the program to remove the riparian vegetation has used points from the channel, thus ...
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1answer
49 views

Is it better to take the elevation of a GPS unit or that of a Digital Elevation Model?

When searching of gps routes in wikiloc, for the trailrunning race "Transvulcania" I have several routes to look. I downloaded a lot, but every route has a distance between 71 kilometers and 74 ...
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2answers
61 views

Reversing Extract by Mask in ArcGIS for Desktop? [duplicate]

I have a DEM and I want to apply some tools to it (fill and others). In my DEM I've zones (drawn as mask) that need to be exlcluded from that processing. I don't want to apply the processing to the ...
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1answer
43 views

Merging USGS DEM files in ArcMap?

I'm trying to merge my DEM files into 2 separate files, one will have 4 files and the other will have 3. I've been reading every post from when someone asked this before for over an hour and I'm still ...
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2answers
50 views

QGIS - Edit Surface DEM to Add Buildings

Okay, let me start by saying I'm no expert in QGIS, I'm more into engineering. I'm building a 2D hydraulic model and I would like to add the building footprints (elevated) to my DEM, so flow will go ...
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26 views

Performing DEM analysis?

My DEM elevation values varies from -255 to 81. What does the negative values imply? I have downloaded the dem from BHUVAN. About 90 % of values fall in negative category. How can I convert these ...
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29 views

Merging DEM files using PostGIS

I have several DEM files and I want to merge them to create a mosaic. I found the St_Union(raster) or St_MemUnion(raster) functions but I don't know how to use them. Are there any other solutions?
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37 views

From DEM to Topographic Wetness Index in SAGA GIS

I have DEM in GeoTIFF format and I wish to calculate Topographic Wetness Index in SAGA GIS. TWI tool in SAGA GIS expects that user provides two values - 'slope' and 'catchment area'. Since there's ...
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1answer
55 views

Understanding InSAR interferometry?

I understand that the result of InSAR interferometry yields a LoS deformation and if deformation in the vertical or horizontal is to be computed, it should require additional gps observations at the ...
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0answers
22 views

Export of a Raster Not Preserving Color [duplicate]

I'm trying to make a pretty shaded relief map using the technique described here. I've done this process several times in the past without any problems but today am perplexed about what is going on. ...
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54 views

SRTM DEM and satellite DEM fusion

I have a SRTM DEM and a DEM derived from satellite (Cartosat). Both the DEMs are registered perfectly. Now I want to carry out a DEM 'fusion' process to derive a higher quality output DEM. I am not ...
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2answers
154 views

Does a SRTM DEM image show details such as fields?

I'm working through the QGIS Training Manual where I have a step to get ... ... raster images (SRTM DEM) which cover the region you have selected for your course. SRTM DEM can be ...
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1answer
73 views

How to find the coordinates of the lowest point in a polygon

I am working in QGIS 2.6. I have a file of several polygons and I want for each one, to find the lowest point (where is it located and its elevation). I am using "Grid statistics for polygons" which ...
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147 views

Can the Phantom 3 Pro be used to capture aerial imagery for small site plans and to derive DEM?

I am curious if this consumer UAV can be used to capture imagery for further processing to stitch seamless imagery and to use as input into stereo/photogrametry software to create reasonably accurate ...
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34 views

Calclulate the shade from a DSM and from sun elevation and azimuth angle

I have a mosaic of about 5000 tiles of aerial orthophotgraphy taken at different dates and thus with different sun angles. Furthermore, I have a Digital Surface Model (1 m resolution). My goal is to ...
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1answer
150 views

How to fill holes/missing values in XYZ data / a DEM with QGIS?

I have equidistant XYZ point (text) data that I used to create a point grid. However, it's not perfect - there are some holes. I then created a DSM raster from it, which obviously has the holes too. ...
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2answers
48 views

Classifying DEM using Height Differences in ArcGIS ModelBuilder?

I would like to classify DEM into some classes, into a shp file with equal intervals of 200m (0-200m, 200-400m, 400-600m... 3400-3600m, higher than 3600m), by using Model Builder in ArcGIS 10.2. For ...