Hey everyone!
I would like to add more than one raster on my terrain like the screenshot following:

But when i am integrating them the rendering does something like that:
We just see the layer on the top of all others but there is no transparency anymore, while when I we created those raster there are supposed to supperpose like the screenshot below:
Does anyone know if there are any settings to consider to apply some kind of transparency between raster and to be able to see all my rasters in the same time?
Hi @Emma.R,
Check in your material instance and confirm that each layer is using the MLB_CesiumAlphaBlendBaseColor blend asset. That asset uses the layer’s opacity parameter to handle the transparency. If you are already using that blend asset, then it’s possible that your raster overlays are set up differently. Try duplicating MLB_CesiumAlphaBlendBaseColor and using the Opacity Mask, rather than Opacity, to drive the blend.
-Alex
@Emma.R just to check, have you assigned each raster overlay a different “Material Layer Key”? The bottom layer should be set to “Overlay0” and the top to “Overlay1”.
Hum, i didn´t find those options, but by clicking on “refresh Tileset” it actually provides me the transparency i wanted, i don´t know really why 
Thanks anyway!
-Emma
I tried that, and it works for 3 layers but not for the fourth one
Yes the default material only supports 3 raster overlays. You can define a custom material with more, but eventually you’ll run out of texture units.