Wrong size of legend symbols size and map symbol when using geometry generator on a point layer

[gwenandres]

Hello,
I get really big symbols in the legend on a point layer with surface or line geometry generator when I choose categorized symbols.

For example :

• I create a new point memory layer
• I add a column "type" (integer)
• For style, I choose categorized symbols on "type" column
• For symbols, I choose surface geometry generator (buffer ($ geometry, 2))
• Then in legend I get really big symbols for each type.

I am working with QGIS 3.4.14 LTR on Windows 7 or 10.
I try with QGIS 3.10.1, I have the same behaviour.

[gioman]

@gwenandres your layer has a CRS that has degrees as units?

[gwenandres]

The CRS is 2154 so it has meters as units.

[gioman]

@gwenandres Can't confirm here on 3.10.1 on Ubuntu 18.04 but I'm not totally sure I followed the exact steps that lead you to see this problem.

[gwenandres]

@gioman Sorry if I am not clear. I have the problem on a point layer, not on a surface layer.

Yes it can be strange but I have point layer with surface generator.

[gioman]

I have the problem on a point layer

@gwenandres oh I see... moreover not only the legend symbol does not make sense, but also the generated area on map is not visible at all.

[SrNetoChan]

I was able to replicate this. It only happens on Rule-based (maybe categorized too) Symbol, but not in single symbol, where it works just fine.

[jonnyforestGIS]

@SrNetoChan I confirm as well this behaviour when using the geometry generator and happens with categorized symbol. Cheers

[jonnyforestGIS]

@gioman having this #39777 as a possible resolution for this issue, this ticket can be close?

[gioman]

@gioman having this #39777 as a possible resolution for this issue, this ticket can be close?

@jonnyforestGIS have you tested the fix using the scenario described in this ticket?

[jonnyforestGIS]

@gioman you're right.
I did a tested with the master and change the options but the behaviour with the new options but the issue still there. Please see my comment in #39777 , I will wait for @nirvn to answer, maybe I'm doing something wrong. Cheers

[SrNetoChan]

I have confirmed this on master. @Nirv fix does not fix the issue when the geometry generator is uses in categorised, graduated or rule based renderers. But works like a charm for single symbol renderer

[gioman]

See also #29119

[SrNetoChan]

I guess we can close one as duplicate.

[gioman]

I guess we can close one as duplicate.

already did :)

[sickel]

I can confirm the same behaviour in 3.20.3. Using a postGIS point layer with a generated polygon around the point.
I just opened the same project. The height seems to be cropped, the symbols are too wide,

After collapsing and reopening the legend, it looks like this:

This is the symbol definition:

The dataset is in WGS84. The generated geometry is made by another geometry in the the same postGIS table.

[Pedro-Murteira]

I can still replicate this on QGIS 3.16.14 and 3.22.1.

[SrNetoChan]

There is an option to limit the size of the legend patches in the layers panel (settings > options > Map and Legend > Layer legend > Legend maximum size).

It seems to work fine for symbols where the size is controlled by an expression, but not by geometry generators.

In this project, this is clear
https://mega.nz/file/5MFkERjQ#OXEO-g6oUypng9eMvx1KDHA4lRmMbC8gKN40gz6dMcc

[martyvis]

Looks like there is a general problem with Geometry Generator scaling I am seeing as well. I have a Point layer and I add a simple square using Geometry Generator expression as follows 👎
make_line($geometry, translate($geometry,0,10.0), translate($geometry,10.0,10.0), translate($geometry,10.0,0.0), $geometry)

With Map Units set and using a CSR of EPSG:3857 (WGS84/Pseudo Mercator) you would expect the square to be 10m by 10m. Instead it looks like it is maybe 10 degrees x 10 degrees?

Running 3.24.2-Tisler on Windows 11

[nyalldawson]

@martyvis

Is your layer in 4326? The geometry generator map units refer to the layer's units.

[martyvis]

@nyalldawson Yes it was. I think I have worked out I had a workflow issue. When I create a new layer, usually a scratch layer I change its Geometry Type (say to Points) and add fields if needed but don't change the CRS. Somehow I thought the scratch layer would have followed the map layer I had underneath. I worked out if I change the CRS (eitger on creation or afterwards, it all works). The thing I still notice though is they if you open Geometry Generator expression build and look at the "map_units" variable it shows it as being "meters". So obviously this isn't correctly reflecting the Map Units that the layer is using. (Also if you have the layer selected and move your mouse the coordinates in the bottom still show metres and not degrees.

[CharlesGag]

Still happening in 3.36.1

I have this symbol, everything works fine

If I use the same one, but categorized, I get this :

I use EXIF data to generate these points so the layer is in 4326, but my projet is in another projection.