Add "dynamic elevation range per band" mode for rasters (Request in QGIS)

[qgis-bot]

Request for documentation

From pull request qgis/QGIS#56900
Author: @nyalldawson
QGIS version: 3.38

**Add "dynamic elevation range per band" mode for rasters **

PR Description:

This accompanies qgis/QGIS#56889, and exposes a new mode where the elevation range for raster bands are calculated using a pair of qgis expressions (for the lower and upper elevation range).

In this mode, the user can specify a QGIS expression for the lower and upper value corresponding to raster bands, using variables like @band, @band_name and @band_description.

E.g

@band * 100

Can be used when each band represents a 100 m vertical slice of data. (You can mix these with all the other standard qgis global/project/layer variables and expression functions)

The expression will be evaluated when required to determine the actual elevation range corresponding to each band.

This differs from the other "Fixed Elevation Range Per Band" mode in that "Fixed Elevation Range Per Band" requires users to manually enter an elevation for each band separately, and these values are then treated as constants. That mode works best for rasters with non-regular steps in the band elevation values, while this new mode is better for regular band elevation steps.

Commits tagged with [need-docs] or [FEATURE]