Currently it is hard to get correct colors for large amounts of buildings to show in 3D in ArcGIS Pro or City Engine. I propose tools to do this. One would select colors from a list and the other would apply colors from Imagery. By using colors instead of textures in City Engine/ArcGIS Pro and scenes online, the draw time is much faster on procedural buildings.
The first tool to allow you to select building polygons and choose among many colors (hex) to assign to the buildings randomly. A field would be added (default SideColor) and you would choose from an extensive list of colors with a weight on it for the percentage of buildings you wish that have that color. You would select the buildings in the area, check against Bing's Bird's Eye or Google or streetview of the colors used in that area on the sides of buildings.. Then you would weight the percentage with the colors selected. The percentage would change as new ones were added (if you add 5% to a new one, all others selected would dropped by 5% to result in the total selected percentage to be 100%). The tool would take those colors and percentages to apply randomly to the building footprints.
Enter Building Footprints: Buildings_Footprints
Enter Field to add and assign random hex colors to: SideColor
A second tool would use a resampled segment mean shift image to get the roof color from the imagery and apply it to the polygon field (default RoofColor). It would take the centroid inside of the polygon to get the RGB color from the Segment Mean Shift of the resampled high resolution imagery and then convert that color to hex to populate the field. A prototype of the tools is at Arthur's Feature Extraction from LiDAR, DEMs and Imagery