The Making Of "Electricity Of Life"

Torches, Electricity, Fern, and Background Trees

One area where I have been developing skill is in the use of filter maps to create highly natural objects. My workshop on "Voyage of the Ferns" discusses some of the basic image processing techniques I had developed for this purpose. However, "Electricity of Life" required a further elaboration of the image processing and mapping techniques evolved for that work.

First came the development of the flame. For that I used the ImageFX flame generator.

Initially, I used the masking technique I had developed for "Voyage", but it quickly became clear this was inadequate for a flame. This was because the flame did not have a solid edge like a fern, but instead faded into the area with gradually increasing transparency.

I tried a number of techniques, such as the use of Gaussian blur, to create a soft edge to the flame mask. Unfortunately, those techniques all increased the size of the filter mask, which, instead of creating a gradual increase in transparency, actually ended up creating a fringe of object color above the flame. Finally I realized that a manual technique was needed.

	Create the flame. In this case the flame was shaped to mostly fit the buffer.
	Change color: 0,0,0 to 0,0,0 closeness 217; this makes all the black the same black, though it also sharpens the edge of the flame. That will be dealt with in the filter map. Save the flame as the primary image.
	Negative the flame. If the wood flame palette is used, this image is largely blue, with the black background now a convenient filter white (which lets all colors through).
	Change color: 0,0,255 to 0,0,0 closeness 239; this makes all of the flame black
	Negative the image. The flame is now white. Select black from the palette and double-click on flood fill. Set the feather in to 14. Flood fill the flame. Flood fill the detached parts of the flame.
	Flood fill the "sky" with white, no feather. Fill the "holes" in the flame. Extend the black to the edges if you want a seamless map (as I needed for the cylinder). The filter map is ready. Save it to disk.

Theoretically a Rexx script could be written to automate the process. In practice, when creating an animated flame, 10 frames of animation should be sufficient, and the process can be done by hand (though it is most convenient to do all the flames first (with AutoFX) and then create the filter maps for each frame).

Torch model showing light source axis above flame cylinder (needed because the light source casts shadows and will be blocked by the opaque parts of the filter map)
Torch at night shows flames on the other side of the flame cylinder	Torch in daylight allows you to see how well the filter map makes the flame edges transparent

The lightning was much easier, because of its much smaller color variation. Once I created the lightning, I then negatived the image, converted it to greyscale and then back to RGB, and saved the result as the filter map.

The fern essentially used the same technique described in "Voyage". However, the result was mapped on a disk with a glass refraction index which was subsequently placed inside the glass sphere.

Finally, the row of background trees was done in an even simpler way. A photo of a bare tree line was cropped, greyscaled, negative gamma'd several times, and then RIP was used to remove isolated pixels, and some painting was done for branch segments separated from the trees. Change color was used (255,255,255 to 255,255,255 closeness 146) to ensure a white sky (letting all color through when used as a filter). This black silhouette was then simply used as a filter map on a plane, which, in letting the blue sky through, gave a fine atmospheric perspective to the background. I also decided to repeat and mirror the filter map, which provided an interesting taste of artificiality to the background - in fact, the trees sometimes ended up resembling Richard Dawkins artificial life "biomorphs" (which were first programmed on an Amiga). That was a symbolic echo that I thought fit quite well with the rest of the content.