Bug report #14597

Grid Interpolation requires Real data type with decimals for Z value

Added by Guillaume Larocque over 3 years ago. Updated over 1 year ago.

Status:Closed
Priority:Normal
Assignee:-
Category:Processing/GDAL
Affected QGIS version:2.14.0 Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:worksforme
Crashes QGIS or corrupts data:No Copied to github as #:22565

Description

In QGIS 2.14 with the Grid (Interpolation) dialog, only fields that contain decimals appear in the available fields for Z values. In previous version, one could interpolate from integer data types or with real column with zero precision.

Elevation_Points.zip (47.7 KB) Guillaume Larocque, 2017-01-24 10:16 AM

QGIS_Issue14597.png - Column "ELEVATION" selected as a Z field. (248 KB) Eurico Nicacio, 2017-01-25 09:49 AM

Screenshot_from_2017-01-25_13-12-41.png (72.5 KB) Guillaume Larocque, 2017-01-25 10:07 AM

History

#1 Updated by Giovanni Manghi over 3 years ago

  • Status changed from Open to Feedback
  • Category set to GDAL Tools

I believe you refer to the tool in the "raster" menu, "analysis" sub menu, right?
If yes, what about the same tool when used from the Processing toolbox?

#2 Updated by Giovanni Manghi over 3 years ago

  • Status changed from Feedback to Closed
  • Resolution set to worksforme

seems to work as expected in both the raster menu and in Processing, at least on 2.14.3 and master.

Please reopen if necessary.

#3 Updated by Guillaume Larocque almost 3 years ago

  • Status changed from Closed to Reopened

Still does not work in QGIS 2.18. Tried on all platforms and if a field does not have at least one decimal, it will not be selectable as a Z field in the Grid (Interpolation) dialog. The workaround is to make sure that the data type of the field is real AND that the precision is at least one.

#4 Updated by Giovanni Manghi over 2 years ago

  • Category changed from GDAL Tools to Processing/GDAL

#5 Updated by Alexander Bruy over 2 years ago

  • Status changed from Reopened to Feedback

Can you be more precise, which tool is broken? Just tested GDAL and native QGIS tools and both works fine

#6 Updated by Guillaume Larocque over 2 years ago

I just tried it again with the attached Shapefile. For instance, the ELEV column is not selectable in the Grid (Interpolation) Raster menu item in 2.18.3 as a Z field. If you copy that column into one with decimals, it will then be selectable.

#7 Updated by Eurico Nicacio over 2 years ago

I just tried with the shp provided in both the Raster menu and in Processing, using QGIS 2.18.3 on Ubuntu.
It works properly, as you can see in the image below.

#8 Updated by Guillaume Larocque over 2 years ago

Weird, if I do the same thing on my computer running QGIS 2.18.3 on Ubuntu, I only get PROVIDER and TYPE as options for the Z Field with that file. See attached.

#9 Updated by Alexander Bruy over 2 years ago

  • Status changed from Feedback to Closed

Works fine with Processing front-end. GDAL Tools is a deprecated plugin, use Processing instead.

#10 Updated by Guillaume Larocque over 2 years ago

  • Status changed from Closed to Reopened

This is still a problem in 2.18.4. I gave a QGIS workshop and all 12 participants had this issue on all platforms. If the column type is INTEGER, it does not show in the list of fields in the Grid (Interpolation) dialog. The Processing Grid (Inverse distance to a power) option does not even allow to specify the output raster resolution and extent, so is not a suitable replacement.

#11 Updated by Giovanni Manghi over 2 years ago

  • Easy fix? set to No
  • Regression? set to No

#12 Updated by Nyall Dawson over 1 year ago

  • Status changed from Reopened to Closed

This won't be fixed for 2.18 - it works fine in 3.0.

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