arcpy - How to achieve that symbols have a fix size and are not scaled when zooming

lbd_bayern — Wed, 17 May 2023 06:58:55 GMT

Hello all.

I wrote an arcpy script to change the symbols for the (point) data of a layer.

I am able to adjust the size of the symbol, its color, its outline width, its outline color, and also to replace the symbol with another symbol from the gallery.

However, what I have not been able to achieve is to set the symbol size to a fixed size such that it is not scaled when zooming - i.e. the symbol should get bigger when zooming in and smaller when zooming out.

In the documentation of the symbol class (https://pro.arcgis.com/de/pro-app/latest/arcpy/mapping/symbol-class.htm), the property useRealWorldUnits is listed which - from the description - should be exactly what I need. However, the use of

symbol.useRealWorldUnits = True

has no effect, the symbols are still scaled (I also tried setting the boolean to False but this also does not change anything).

Here an excerpt of my code, already having the reference to the layer for which I want to alter the symbol:

symbology = layer.symbology renderer = symbology.renderer symbol = renderer.symbol symbol.size = 100 symbol.useRealWorldUnits = True # does not work..? symbol.color = {'RGB' : [255, 0, 128, 60]} symbol.outlineWidth = 0.2 symbol.outlineColor = {'RGB' : [255, 0, 0, 60]} layer.symbology = symbology

and its effects in ArcGIS Pro:

1. Before running the script, the map looks like this:

2. For testing purposes, I alter the symbology for a point data layer such that the symbols are huge (and also have a very noticeable color):

3. When zooming out, the symbols are scaled and consequently cover a lot more area in "real world units":

Does anyone know how I can fix the symbol size to the real world units by use of arcpy?

I am using ArcGIS Pro 2.9.2, and the arcpy version is also 2.9.2.

Re: arcpy - How to achieve that symbols have a fix size and are not scaled when zooming

Sven_Harpering — Wed, 17 May 2023 07:35:55 GMT

Hi,

in my opinion you have to use the property "referenceScale" on the map. Looks like this:

aprx = arcpy.mp.ArcGISProject(r"CURRENT") map = aprx.activeMap map.referenceScale = 5000

Now the symbols have a fixed size in the map. I am not sure if you can set a fixed size for the layer directly.

Re: arcpy - How to achieve that symbols have a fix size and are not scaled when zooming

lbd_bayern — Tue, 23 May 2023 12:38:52 GMT

Hi @Sven_Harpering ,

thanks so much for your answer (and sorry for my late response). Using the "referenceScale" does the job for me and is sufficient to achieve the desired result. Cheers!

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arcpy - How to achieve that symbols have a fix size and are not scaled when zooming

Re: arcpy - How to achieve that symbols have a fix size and are not scaled when zooming

Re: arcpy - How to achieve that symbols have a fix size and are not scaled when zooming