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13 votes
Accepted

Assigning z values to depth curves in QGIS

It's super-easy in QGIS 3.0: Run the "Set Z Value" Processing algorithm Click the button on the right of "Z Value", and select Field -> "DYBDE". Run the algorithm. The z values for the geometry's ...
ndawson's user avatar
  • 27.7k
10 votes
Accepted

What is the meaning of this linear scale of angles on this 1951 map of Iceland from the U. S. Army Map Service (AMS C762)?

I believe it is actually used to generate a Magnetic north line, using the reference point P on the bottom edge of the map. At least that's how I interpreted the statement in the declination legend (...
Steven Kay's user avatar
  • 20.4k
6 votes
Accepted

Topographic Position Index unexpected result in QGIS

I think the problem is related to how you change the projection of your data. If the DEM data was originally in geographic projection (WGS84), and not projected to UTM zone 10S, then you need to ...
ahmadhanb's user avatar
  • 40.9k
5 votes

How do I assign a height to each individual contour line using QGIS. Raster > Extraction > Contour

If you are using QGIS 3.10 or later, you have better control over the GDAL tools - See the visual change log. It means, GDAL-Contour tool can take direct input from users to which elevation (height) ...
Kazuhito's user avatar
  • 30.9k
5 votes
Accepted

Reproducing terrain ruggedness index from the original paper example

I hate the be the bearer of bad news but, Riley et al., (1999) is wrong. The ruggedness index itself is fine but, the example in the paper is incorrect. Obviously, the reviewers did not work through ...
Jeffrey Evans's user avatar
5 votes
Accepted

Searching for waterfalls / water drops within an area of interest, return location and height

One possible option would be to use OSM-Data (Open Street Map Data) and to rout your user's search request trough e.g. the Overpass API. It will return e.g. waterfalls for a given AOI, including names ...
Vincé's user avatar
  • 1,414
5 votes
Accepted

QGIS smooth mapzen DEM to create a very simplified topographic map

Solution 1: Discrete layer Styling Simply create the effect using layer style: set it to singleband pseudocolor, choose a white to black color ramp and manually classify depending on the elevation ...
Babel's user avatar
  • 71.6k
4 votes
Accepted

Positive Topographic Openness - do any FOSS tools (other than SAGA) provide this?

In GRASS GIS 7, there is r.skyview addon for sky-view factor, which is very similar to openness. You can check the implementation details here. Download the addon with g.extension r.skyview.
Anna's user avatar
  • 901
4 votes

QGIS Print Layout doesn't show elevation labels

Thanks for the thumbs down. In case anyone is facing the same issue, in my case, the problem was that I was trying to use a different page size in the Print Layout, which causes the labels to change ...
David Martins's user avatar
3 votes
Accepted

Raster appears smooth when created but pixelated when opened again

ArcGIS has a raster layer display resampling feature. Assuming the spatial resolution is the same for the input and output raster data, the 3D Analyst output likely has either Bilinear Interpolation ...
Aaron's user avatar
  • 51.7k
3 votes

Gdal: how to get the max and min altitudes of my topographic raster?

Using gdalinfo and jq you can get what you need in a succinct fashion. This assumes that band that has your min/max is the first one (change the index if not). gdalinfo -json -mm input.tif | jq ....
Marc Miles's user avatar
3 votes

Can we create topographical map of private land using GPS elevation data?

In the hope that new available datasets will be of help to others who are looking to achieve these results, here's my two cents: To the question "Is there a way to create a relatively precise ...
Gabriel's user avatar
  • 3,145
3 votes

What is Google source for United States topographic data?

In the US, it appears that Google is using LiDAR data where it is available. I ran some tests in two areas. One where I had actual LiDAR data, the other where I had field survey data. Google ...
Lance Maidlow's user avatar
3 votes

Calculating sunrise/sunset time while considering topography

I installed the ephem python package in my GNU/Debian Linux System and, I could use it at the Python Console of QGIS. I created an observer for a point near of Utah Lake (USA) and it was calculated ...
xunilk's user avatar
  • 30k
3 votes

Determining best neighbourhood search radius for Topographic Position Index (TPI) for predictive soil mapping?

There really is no expected for this unitless metric. The TPI is the delta of the focal pixel from the mean of the focal window. Obviously, the metric is sensitive to outliers and the larger the focal ...
Jeffrey Evans's user avatar
3 votes
Accepted

Generate Height Above the Nearest Drainage (HAND) using QGIS

Actually, I did not generate HAND from DEM before, but based on High Resolution Hydrography and Hydrologic Modeling PDF reference file, they use TauDEM tool accessed from ArcGIS, as you can see in ...
ahmadhanb's user avatar
  • 40.9k
3 votes

Adding topography to base maps using Surfer?

To add the BLN file to your map in Surfer version 14 or 15, select the map you want to add it to, and then click Home | Add to Map | Layer | Base, select the BLN file and click Open. A new base layer ...
Kari Dickenson's user avatar
3 votes

Combine multiple USGS topo quads into a single seamless raster?

Rather than using individual US Topo quadrangles (which are designed to be displayed in that format), you can download the underlying vector data from The National Map and customize the extent of your ...
Nathan's user avatar
  • 1,304
3 votes
Accepted

What happened to buildings on USGS topo maps?

FAQ States: The original USGS 7.5-minute (1:24,000 scale) Historical Topographic Maps (produced 1945-1992) included feature classes that are not yet shown on US Topo maps (produced 2009-present)...
Mapperz's user avatar
  • 49.9k
3 votes

How do I assign a height to each individual contour line using QGIS. Raster > Extraction > Contour

Use GRASS r.contour and you can input the contour levels you want: Or use GDAL contour, then select using an expression, edit and delete the lines you want/dont want.
BERA's user avatar
  • 73.9k
3 votes

Create a topography map base in QGIS

For QGIS I was able to add the plugin 'quickmapservices' which gives me access to different basemaps: OSM, Nasa, etc. I was able to add the OSM Cyclemap to the base layer using the 'quickmapservice' ...
KLee's user avatar
  • 61
2 votes

How to do diagram block with open source software?

This strongly depends of the data structures you have. I think some voxel reperesentation is required for the kind of diagrams you mention. Perhaps GRASS GIS is a worth a consideration: https://grass....
Jochen Schwarze's user avatar
2 votes

Quebec GIS Data

Forêt Ouverte has topographic (LiDAR-derived) data available to download for free. The spatial resolution of the DEMs is 1 meter, and can be downloaded by tile from the ftp link provided in Catalogue &...
FSimardGIS's user avatar
  • 3,836
2 votes

Quebec GIS Data

The page is in French, but you can find a lot of geographic data on the Ministère de l'Énergie et des Ressources naturelles's site: Répertoire des services Web et données géographiques Borders can be ...
Greg Sadetsky's user avatar
2 votes
Accepted

Seamlessly merging USGS DEM data with higher resolution survey?

Create outline of new dem convert to polyline Create transition zone buffer around it. to polyline Interpolate shape using old dem Interpolate shape using new dem Triangulate using both. Map ...
FelixIP's user avatar
  • 23.1k
2 votes

How would I determine my search radius when conducting a Topographic Position Index in SAGA GIS?

It is good you started to work with TPI on SAGA, since it is rare software which cares TPI's scale-dependent nature. In the poster linked below you will find answers. Andrew D. Weiss Topographic ...
Kazuhito's user avatar
  • 30.9k
2 votes

Seeking European Mountains Shapefile

There is a dataset available for all European mountain ranges on https://www.eea.europa.eu/data-and-maps/data/european-mountain-areas
ebcs's user avatar
  • 49
2 votes

Determining best neighbourhood search radius for Topographic Position Index (TPI) for predictive soil mapping?

I would think that there are a number of factors to consider: Point Data Density Size of area to be mapped Intervening feature size to be ignored Available computing power vs available time Degree of ...
Steve Barnes's user avatar
2 votes

How to fix unusual initial DEM input values and derivative raster output values in SAGA GIS without rescaling?

It seems SAGA has an issue with its Import Raster function to read GeoTiff tags. The strange NoData value (-3.40282e+038) is probably (-32767) in the original dataset. As already pointed out by @Rex,...
Kazuhito's user avatar
  • 30.9k
2 votes

How big is the error of relative elevation between two points taken from GPS relative to taken from a topographic survey?

There is no reason why survey-grade GNSS equipment cannot be used for elevation. The required accuracy, however, will determine your positioning strategy and also duration of observation collection. ...
JimT's user avatar
  • 2,383

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