25
votes
Accepted
Interrupting contour lines beneath elevation labels (instead of using label buffers) using QGIS?
Yes, doable. Normally I'd suggest a partially transparent buffer, but I see why you want to do this cartographically.
This could be slow, and you need to manually decide where you want the labels to ...
- 20k
21
votes
Accepted
Meaning of "Elevation above surface of ellipsoid"?
The elevation above the ellipsoid (ellipsoidal height) is the elevation above a mathematical model that approximates the shape of the earth. The current most common one is WGS84. These are the ...
- 3,051
14
votes
Seeking alternative to Google Maps Elevation API
I've been working on opentopodata.org as a free, open alternative to the Google Maps Elevation API.
Request URLs look like this:
https://api.opentopodata.org/v1/eudem25m?locations=51.875127,-3....
- 319
13
votes
Accepted
Obtaining elevation data for points using QGIS
Basic steps to get elevation data in GPS points:
Obtain an elevation raster for your area of interest. You'll need a DEM (Digital Elevation Model) raster, which is a raster of pure elevation data ...
- 23.8k
12
votes
Accepted
Querying Elevation Data in Postgis
Your elevation points are definitely regularly aligned and hence there is no need to bother about nearest neighbors. The value of the pixel in which your point fall into is always the value of the ...
- 2,512
10
votes
Accepted
Converting sign for a 32-bit GeoTIFF with an open source tool?
I don't know if this is the easiest way, but one way would be to use gdal_calc.py from GDAL:
gdal_calc.py -A positive_values.tif --outfile=negative_values.tif --calc="A*(-1.0)"
- 2,252
10
votes
Accepted
Elevation from TIFF file
Save the Excel file as CSV
In GIS, add the CSV file to QGIS using "Layer > Add Layer > Add Delimited Text Layer"
Use "Sample raster values" from "Processing Toolbox (...
- 68.3k
8
votes
Seeking free elevation data for Europe?
In 2016, the Japan Aerospace Exploration Agency (JAXA) released a new free 30 m (1 arcsec) resolution global topographic data set called ALOS Global Digital Surface Model "ALOS World 3D - 30m" (AW3D30)...
8
votes
Accepted
Subtracting out slope (in general) of DEM using ArcGIS for Desktop?
Subtract the trend surface from the DEM.
Linear trend (1st order polynomial)
2nd order polynomial trend
Per @radouxju's comment - the trend line can be shifted down to avoid negative values by ...
- 58.2k
8
votes
How to create contour lines from point data using QGIS?
Using the Contour plugin. Generate isolines and/or filled contours a set of data points.
- 339
8
votes
Accepted
How to find all points with certain elevation difference between them in QGIS
The easiest way is to import your points into a format that can be queried with SQL, like PostGIS, SQLite or Shapefile (using OGR).
Then you can query:
SELECT *
FROM [table] a, [table] b
WHERE a.[...
- 3,051
8
votes
Accepted
Getting elevation at particular coordinate (lat/lon) programmatically (but offline)?
You can use the rasterio library:
import rasterio
coords = ((147.363,-36.419), (147.361,-36.430))
elevation = 'srtm_66_20.tif'
with rasterio.open(elevation) as src:
vals = src.sample(coords)
...
- 58.2k
8
votes
Accepted
Determining if shapefile has elevation or z coordinate values stored using ArcGIS Desktop?
Your question title and content are a little ambiguous as to what you are asking. As for checking to see if a shapefile has z information, which seems to be your ultimate question, is as follows:
...
- 5,747
8
votes
Accepted
QGIS - Lakes - Change Polygon Z values, using Single Field Value
In QGIS 3.0, run the "set z value" algorithm. Hit the button next to z value and select the field containing your desired z values.
- 27k
7
votes
Identifying south facing mountain land, above an elevation, within a slope range, less than fixed distance from major roadways
The following is a rough outline of what you might do. I won't include a great deal of detail, you can research further using these terms and/or ask new more specific questions.
Note: you will need ...
- 58.2k
7
votes
Interrupting contour lines beneath elevation labels (instead of using label buffers) using QGIS?
During my research to achieve a mostly dynamic labeling of contour lines in QGIS 3.10, I put everything together in a small cooking recipe and changed my original answer to share the findings with the ...
- 4,586
7
votes
Extracting elevation from .HGT file?
GDAL can read/write these raster formats with the SRTMHGT driver. This means you can view the raster with QGIS, ArcGIS, or use GDAL utilities like gdallocationinfo to get values from a point, e.g.:
...
- 41.1k
7
votes
Accepted
Find lakes on an elevation raster
In your comments above you expressed interest in my suggested method, and so I am providing a more detailed answer here. The method uses the tools available in Whitebox GAT, the open-source GIS that I ...
- 10.9k
7
votes
Accepted
Which is better for measuring actual ground elevation, NED or SRTM?
This is by no means an answer to your specific problem but an explanation of elevation data and vertical accuracy. Also, this all wouldn't fit in a comment.
Only a select number (depending of area ...
- 5,747
7
votes
Accepted
Inaccurate altitude GPS data with my Android?
There could be a number of problems in play here depending on where you are, what the terrain is like, and what the capabilities of your device are?
If your device uses pressure sensors they may not ...
- 3,521
7
votes
Creating Buffer Polygon following Elevations using ArcGIS Desktop?
Workaround for what you describe in absence of spatial analyst:
arcpy.Buffer_analysis("target","../buffer.shp", "100 Meters")
arcpy.FeatureVerticesToPoints_management("buffer","../points.shp","ALL")
...
- 22.2k
7
votes
Getting correct elevation values from Digital Elevation Models
It's impossible to pinpoint what is going on without looking at the data per se, but a wild guess would be due to the DEM being a DSM and not a DTM. I don't know how well you know these terms, but on ...
- 3,071
7
votes
QGIS: Edit elevation in DTM to get correct slope of a river
Create a new shapefile having the same CRS as your DEM. Create a numeric field (Whole number or Decimal number), like heightadd, and Add to Fields List.
Draw a polygon on the area you want to add ...
- 30.3k
7
votes
How to exaggerate the elevation in QGIS 3.6?
I suggest that you use a Hillshade symbology for the SRTM and then try using Multiply blending (put the SRTM layer on top in the Layer List). You can exaggerate with Z-factor:
- 2,546
7
votes
Elevation Profile with labels on waypoints (QGIS, Python)
Using your xml file and matplotlib you can achieve nice results if you put some effort in it. Matplotlib plots can be tweaked to look alot like your example. The trickiest part was to calculate where ...
- 60.5k
7
votes
Using gdal to interpolate elevation from a GeoTIFF
A high-level rasterstats tool is built on GDAL to fetch data from raster and vector data sources.
import rasterstats
from shapely.geometry import Point
raster = "elevation.tif"
pt = Point(...
- 41.1k
6
votes
Interrupting contour lines beneath elevation labels (instead of using label buffers) using QGIS?
I think the closest it can get with current QGIS abilities is to use halo (or background) effect with color sourced from table which will be based on the elevation value and color scheme same as used ...
- 9,456
6
votes
How to calculate mean elevation in a DEM between a specific interval?
Set environment setting extent=your DEM extent, snap raster = DEM,
cell size= one for DEM.
Use raster calculator expression:
Con("DEM">1500,"DEM)
Right click on resulting raster, Source, scroll down ...
- 22.2k
6
votes
Accepted
Update from/to Z from attributes using arcpy Update Cursor
I think you need to fix your new shape line to contain z values.
newShape = arcpy.Polyline(newGeom, None, True, False)
The default is false
http://pro.arcgis.com/en/pro-app/arcpy/classes/polyline....
- 713
6
votes
Accepted
Latitude above and below the surface of the Earth
No, latitude doesn't follow gravity (as @mkennedy notes, it follows the
normal to the ellipsoid).
And, no, gravity doesn't follow your hyperbolic curve (nor a straight
line).
The simplest model for ...
- 3,176
Only top scored, non community-wiki answers of a minimum length are eligible