I've done a search and not found any references to this so here goes. I have imported a number of raster images into a drawing and wish to turn the "blank" bits transparent. I can set them all to "Background transparency = YES" in the Properties bar, but as far as I can see I need to go through each one individually to set the relevant transparency color, since as soon as I select more than one tile the "Transparency color" tab disappears. Is there a way to do a multiple select as the "blank" color is the same for all the tiles? I'm planning to use a lot of tiles and this will be incredibly laborious and inefficient otherwise. I am using Map 3D 2011.
No, as far as I know, you have to select the Background Transparency per image.
There might be a way to automate this using the Workflow Designer or even LISP - but I'm going to have to refer you back to the community to see if anyone has developed something like this.
Just as a side note: if you have Raster Design, and the Raster tools are loaded, you can use the Raster Design version of transparency. It works mostly the same as the one in Map 3D (you'll see it in Properties when an image is selected, just below the Map 3D transparency option), and I found that it can be more accurate than the Map 3D transparency with certain images.