Timeline for Filtering OSM natural peaks in QGIS
Current License: CC BY-SA 4.0
20 events
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| Jun 23, 2021 at 15:54 | comment | added | Babel | You're welcome. Don't confuse distance tool on the map canvas and the distances used to calculate distances for each layer! Also don't confuse planimetric (cartesian) and ellipsoidal distances. That's why you get different distances. | |
| Jun 23, 2021 at 15:50 | vote | accept | Nebojsa | ||
| Jun 23, 2021 at 15:49 | comment | added | Nebojsa | It seems that this is exactly the problem (although the distance tool gets distances right). In any case, your answer covers everything in case someone else finds themselves in a similar situation. My problem is solved by choosing a very small distance as a workaround, but does exactly what I need. Thank you for the help, I learned a lot from this! | |
| Jun 23, 2021 at 9:35 | history | edited | Babel | CC BY-SA 4.0 |
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| Jun 23, 2021 at 7:28 | history | edited | Babel | CC BY-SA 4.0 |
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| Jun 23, 2021 at 7:12 | comment | added | Babel |
Your peak-layer from OpenStreetMap is probably still in EPSG:4326, isn't it? You changed the project CRS, but not the layer CRS to EPSG:32634. That would explain why changing the max_distance has no effect. Be sure to properly understand the difference between layer and project CRS, see: gis.stackexchange.com/a/392388/88814
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| Jun 23, 2021 at 5:21 | comment | added | Babel | OK, so I guess best would be if you could provide your data (+ your project file, if possible). It's difficult to see what went wrong in your case using my own project and data - in my case, everything works fine. So there must be some setting, but from far, it's difficult to guess. | |
| Jun 22, 2021 at 23:25 | comment | added | Nebojsa | Unmarked as accepted answer. I feel we are on the right track but in the current form, this solution still doesn't solve the issue. | |
| Jun 22, 2021 at 22:51 | comment | added | Nebojsa |
What I did so far: - I used the Field Calculator to add a field called ele_int, and I used the expression to_int(to_real(ele)) to populate it - Then I tried selecting by array_max of overlay_nearest on ele_int instead of ele and I still can't get it to work. I'll update my question with more details. Thank you for helping :)
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| Jun 22, 2021 at 12:30 | comment | added | Babel |
OK, I now see the problem: when you download OpenStreetMap data, you have a field ele for elevation. It is, however, formatted as string (text), not as number, so that's why it doesn't work. You have to convert the values to a integer format first. You could do it directly in the expression, however I would recomand creating a new attribute elevation with field calculator because you also have empty values that can create problems. I updated my answer accordingly.
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| Jun 22, 2021 at 12:30 | history | edited | Babel | CC BY-SA 4.0 |
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| Jun 22, 2021 at 11:32 | comment | added | Nebojsa |
For what it's worth, I get the same results with QGIS 3.16. The number of selected points doesn't change when changing max_distance. array_last ( array_sort( overlay_nearest( @layer, expression:=ele, max_distance:=5000, limit:=100 ) ) )> ele
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| Jun 22, 2021 at 10:37 | comment | added | Nebojsa |
I used QGIS 3.20, and the data I use can be reproduced by importing openstreetmap data using the natural=peak query. To that data, I apply the select by expression, and I do not use array_max but instead the array_last and array_sort sequence. I'm now going to check with 3.16 LTR.
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| Jun 22, 2021 at 10:31 | comment | added | Babel |
Can you provide sample data? Which QGIS version do you use? Be sure to have 3.16 or later - and if you use the version with array_max, you must have 3.18 or later. When I test it, the result changes with different values for max_distance.
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| Jun 22, 2021 at 10:24 | comment | added | Nebojsa | I do have a problem with this kind of query - it works the same regardless if I set max_distance to 1 or 100000. Changing the limit does work and give different results. The map unit is set to meters. @Babel do you have any idea why? I updated to QGIS 3.20 in the meantime. | |
| Jun 22, 2021 at 8:13 | comment | added | Nebojsa | Thank you, I wasn't aware of the "select by expression" feature, nor was I familiar with the scripting language. This answer worked for me. | |
| Jun 22, 2021 at 8:12 | vote | accept | Nebojsa | ||
| Jun 22, 2021 at 23:24 | |||||
| Jun 21, 2021 at 17:51 | history | edited | Babel | CC BY-SA 4.0 |
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| Jun 21, 2021 at 16:54 | history | edited | Babel | CC BY-SA 4.0 |
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| Jun 21, 2021 at 16:45 | history | answered | Babel | CC BY-SA 4.0 |