Hello friends! today we are going to generate DEM from contours in QGIS. This tutorial will help you to generate DEM of any resolution. Happy learning- QGIS WORLD
Thank you, this was so helpful in answering the question of "could it be done." I was wondering a bit more about the "should it be done" part. Is there any rule of thumb for deciding a resolution from something like contours? I have what I hope are contours that are more granular/accurate than a 30m DEM. How do I know if that's the case, and what resolution I could justify?
Thank you so much for the great video. So detailed with a good explanation. Is there any method of using contours and points elevations at the same time to make a DEM?
You are welcome Cherine. You can convert all the contour data to point data and after merging with other point data you have, convert them to contours and then DEM. There are others methods also I guess, which you can get in RU-vid or on other websites. Good luck! Happy learning!
You can download dem file from USGS earth explorer for free. There are several video out there in RU-vid showing the method. And for contour shape file you can generate it from DEM. Good luck!!
Thank you for posting this. Unfortunately with QGIS Fierenza and GRASS 8, the final step (raster contours to DEM) just didn’t seem to work. After I clicked Run, nothing seems to happen. One core of the CPU is busy, but after 12 hours nothing happened. Trying a different method of extracting vertices from the contours, then running IDW interpolation.
@@qgisworld1922 Thank you. It may be because I'm trying to create a 20m DEM over a very large area (8000 x 8000 pixels). The IDW alternative has been running for nearly 4 hours now. But it's hard to know if the algorithm is actually working, or stuck. I'm using a PC with an i7-6700, 1 TB SSD and 32 GB RAM, though it doesn't appear that QGIS / GRASS are set up to make use of multiple cores or larger amounts of RAM. Nonetheless, this is slower than my other computer with a slower CPU running ArcGIS 10.8.x
When I import the contour data after going through v.in.ogr.gis step, Grass 7 pops up and then a windows error message shows: "GRASS 7 has stopped working". Once I click on close program, the layer shows in QGIS but has no attribute data, so I cannot follow with the vector to raster part of this tutorial. any suggestions on how to fix this?
grass.osgeo.org/grass78/manuals/v.in.ogr.html This link might help you finding the solution. Is it possible to send the drive link which include your contour data? We will check it out and find out the problem. Good luck!
If my resolution extent is 12.2103x12.2269, am I ok to continue, or do you have to make it a perfect 12x12? This concerns the mark @3:30 in the video. Thank you
@@qgisworld1922 Thank you... but *why* would you want/need exact, precise 12x12 (compared to it being off by 0.01) resolution? Please explain in detail 🙏
There is no any rule to have a precise 12&12 resolution. The topography doesn't changes noticeably. This is all about, what do you want? 12.2103* 12.2269 or 12*12.
Hei, Can you please help me. How can I have different shape or polygon for the DEM. here you had rectangular but based on my contours its not of a defined shape. i took the rectangular shape and based on that area the contours were extended and was worse
You can clip the generated DEM to any shape you want. Or you can clip the contour to the desired shape and than convert it to DEM. I hope this will help you out. Happy learning
@@qgisworld1922 how can i select a different shape as the region value is to be set based on Easting and northing or extent by dragging on canvas. please help
1.Get the contours which cover the maximum rectangular extent of your desired DEM. 2. After that generate the DEM based on the Contours. 3. Now extract the desired shape of the DEM using the polygon shape you want. If this does not work qgisworld1@gmail.com please email the contours data and the polygon for DEM. Good luck Happy learning
For MAC OS www.qgis.org/en/site/forusers/visualchangelog316/index.html#detect-grass-installation-folder-on-macos Grass setup lesson docs.qgis.org/3.16/en/docs/training_manual/grass/grass_setup.html Good luck sir!
