I'm a software guy (but don't know much about GIS). I'm also a glider pilot in upstate NY. A lot of the glider folks use a simulator called Condor and QGIS is used to help create photo realistic ground scenery....

They seem to have a hard time at it (just blindly following instructions) I just started using it and was trying to create a step-by-step tutorial for them. I'm using QGIS 2.18.28 on Windows 10/64 bit, 16 Gig of Ram. The tutorial is at http://www.murtari.org/downloads/FLSC_SceneryMultiR1.pdf

It has more details, but here are the basic steps up to the hang. Starting with a brand new project:

  1. Layer -> Add Layer -> Add raster layer. I select 6 tiff files of satellite imagery (each about 1.5 gig in size)
  2. Layer -> Add Layer -> Add delimited text. I have a .csv file with 4 calibration points, one in each corner. The selected area is a rectangle 14 miles wide and 52 miles long.
  3. I select the proper coord system: WGS84 EPSG:4326 - OK
  4. Raster -> Misc -> Build virtual raster. I choose the same tiff files. OK (no load into canvas)
  5. Raster -> Projections -> Warp(Reproject). Chose the .vrt created above, Source SRS EPSG:4326, Target SRS our UTM zone 18N, resampling cubic spline (no load into canvas) - OK
  6. Raster -> Extraction -> Clipper. Chose the file from above. Clipping mode 'extend'. Dragged an area inside the calibration dots (load into canvas). OK . I see a red select area inside my dots.
  7. Right click in Layers Panel over name of image above.
  8. Select Save as... Rendered Image, Create VRT, format GTiff, CRS to our zone 18N, uncheck saved file to map. No change to extent.
  9. NOTE - Wanted hi res using 8192.
  10. Resolution (current layer): Columns 8192, Rows 24576
  11. Tiles: 8192 and 8192
  12. Clicked OK - immediately see a small dialog box pop up, the title says "Saving raster... ?" -- nothing else is visible. QGIS hangs, windows says not responding, about 1.5 gig mem usage and stays there....

If the previous stepped work, we would get a tiff of the selected area which with other tools is converted to a .bmp and then merged into a landscape over textured terrain...

  • Welcome to GIS:SE @J.Murtari! How long did you leave QGIS for? It is quite common for it to hang when you see the 'Not responding' message but is actually processing the data. And considering your fairly large target area and resolution value, it may take a while for QGIS to process. – Joseph Feb 15 at 13:41
  • You might also try QGIS 3.4. – Andy Feb 15 at 13:57
  • Andy, thanks for that. I actually did try 3.4, but I'm just following cookie cutter instructions and the 3.4 interface is a little different. I actually thought I was close, but then it still hung. Little more unsure on the reason there since I didn't have a confident work flow.... – J. Murtari Feb 15 at 14:04
  • Joseph, I let it run for about an hour. I was watching it on task manager, CPU usage dropped to zero and stayed there. Glad to hear you say an extended hang could be normal (but I'm assuming there would be CPU activity). Is the data set/resolution requested just too much? – J. Murtari Feb 15 at 14:37
  • 1
    A good way to test your process that is to run the same process on a much smaller data set and/or much lower resolution. Once you get your process to work on a small data set, you can scale up. You might also try automating your process in the Graphic Modeller. Once you have a working model, you can share it with others and all they'll have to do is plug in their own data, turning the 12-step process into a 1-step process. – csk Feb 15 at 20:16

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