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### 3.4 The buildings shadow This chapter develops basically the same process (a bit easier) as for the forest shadows. Refer to the preceding chapter for more details. Select the buildings on the selection map. Save selection to Untitled-1. Rename new channel “Buildings”.
Go to Untilted-1. Duplicate the channel “Buildings”. Rename the new one “BuildingsShadow”. Load channel as selection and invert selection. Use the displacement map from chapter 1.2, or use one you created according to another sun position.
APPLY the “Buildings” channel with invert. LOAD “BuildingsShadow” as a selection inside the “ProjectShadow” document. FILL SELECTION with black.
The shadow map is ready!
### 3.5 Merge the layers At last, we are going to see the result of this long work. It’s time to merge the texture and the shadows. There are many blending modes in Photoshop. I suggest using the “multiply” mode. As the result of this blending mode is much darker than the separate layers, we must adjust the colors. The pictures will be brightened before they are multiplied. The aim is to keep as much as possible the fine terrain relief from the shadow map. It’s a deal : whether you have contrasted texturing, and the fine details of the relief are hidden, or you make visible even the faintest relief’s shades, thus tuning down the texture’s contrast. I suggest some numbers and curves here, which keep some nice relief, but you are free to tweak until you find the best result. Create some adjustment layers linked to each picture layer, so that you won’t loose the original bitmaps. It’s always good to do some attempts on small areas, slice and see the results within Fly!, note the changes to do and come back to Photoshop. It’s now your eye’s job to make the right decisions and this is not easy. And sure some knowledge about color tweaking, color curves and histograms would be very useful. But, if you don’t feel comfortable with colour tweaking, start with the suggested numbers. Open the “Project.tga” file. Adjust lightness and saturation. Some contrast is lost, but it’s needed for better relief shading.
Now we add the shadow layer : go to “ProjectShadow”, hold shift and drag the layer on top of “Project” document. The shadows usually have a faint blue tint because the sky drops some blue light, which is not noticeable in the sunlight. Ask the Impressionists about this point! For this purpose, I made the following curves adjustment. This example needs some tweaking yet, since the deep shadows tend to be too blue. Flatten the curves a little bit.
And the result :
Tune the level to make it much lighter.
Now the long awaited moment, when the final picture is revealed! Set blending mode of upper layer to “Multiply”. Flatten image. Save it as Targa file (.tga)