Main light sources are a window in front of the camera and a light bulb on the right side.
The reflection ball was shot from the desk under the light bulb. The ball itself was directly on the ground.
|I composed the images (shot with different
shutter speeds) in Shake (simple brightnes nodes and expands to get a
mask for copy nodes), saved it as Mental images .ct file and loaded the
float format longitude map into BA_LightDome:
BA_LightDome shows overwhites with a color gradient. e.g. Cyan is for values 16+. The window and the light bulb are far out of range. I choose to chnage no setting of BA_LightDome and directly hit 5. >Optimize points>
BA_LightDome automatically executes 2. and 3. before optimizing. 4. is optional and not used this time (read next Example).
It takes about a minute to search for optimizations. After it finished, I choosed the first optimization from the list, executed 7. >Collape points> and 7. >Reduce lights> (default settings). If you like you can try to skip "Collape points" to get fewer lights in your scene. Then I exported the script file.
Main light sources is the sun at late afternoon and the blue sky.
The reflection ball was shot about 1,50m over the ground. While I shot the ball with lower shutter speeds I realized that my little digital camera is perhaps not able to shoot that high range that I need to darken the sun. The lowest value was shutter speed 1/2000s (with the most closed stop possible, a 8.0) and the sun had still a little glow on the ball.
I composed the images in Shake, loaded it into BA_LightDome:
And there I read that I had a maximum brighness of 3.0 at the sun (mouse location)! The light bulb in the test before had a luminosity of 21! I applied the color (3.) and now "4. Increase luminance at highlights" is used. It increased the luminance at the points that are near the maximum luminance of all points. The sun should be very bright, so I moved the slider "Inc. value" to the maximum. The next important setting is the Highlight color. If I take a look at the image the sun light is orange, which is right cause I had set my camera to "cloud color temerature". The default color is just right for this case. Then I hit the 4. >Increase max Luminance> button. I liked the result and leaved it that way.
If you have a similar problem with low highlights you have to test the values, check the result with the mouse on the image and redo "3. Apply color" if you are not satisfied with the result.
Then 5. >Optimize points>, 7. >Collape points>, 7. >Reduce lights> (default settings) and export to script file.
|This is the result I get. On the first view it looks very nice, but there are some problems. First the shadow. Take a look at the sphere shadow and the real shadow on the background image. The real shadow is a bit blue. That is because it is only lit by the blue sky. XSI's shadow material is only gray. No colored shadows from colored lights.|
|That was the point I wrote my own shadow shader. You can donwload it as a part of the "Binary Alchemy Shader collection". It renders a white image with darker and colored shadow areas. You have to multiply it with the background.|
|Next Problem: if you take a look at the images above (this one is fixed), the ball is very bright on its bottom, but directly under the ball there is ground, which does not emit/reflect that much light on this little area under the ball, and it has dark shadows of the ball. The reason for this problem is that the reflection ball was shot 1.5m above the ground. 1.5m above the ground, a bigger area of ground was reflecting light and there was no shadow under the ball. A probaly solution for this problem could be an ambient occlusion pass between sphere and ground. I this example I have simple reduced the light intensity from below by unchecking the "diffuse" parameter of one light at the bottom.|