Need help modeling extended vision and colorblindness with GIMP and/or PAINT.net

[RobA]

So... vision like the TSA's millimeter wave scanners?

-Rob A>

[waldronate]

Terahertz sensing in a biological system isn't terribly likely because the structures need to be on the scale of the energy to be sensed. Plus, there isn't a good source of energy at those wavelengths out in the universe.

Seeing far into the IR range isn't terribly productive to a warm-blooded creature. Aside from the fogging issues from self-radiation, there's the issue of acuity. Longer wavelengths need larger sensing structures, which means either very large eyes or very poor acuity.

UV causes a problem for protein/DNA-based systems because those high energy photons tend to disrupt molecular bonds (hooray sunburns!) This absorption by molecules tends to limit the amount available for visbility. Not to say that the races wouldn't develop suitable bandpass items, but there is an upper limit to frequency sensing with water/carbon-based life if only because the radiation eventually becomes too penetrating to be captured (think X-rays).

[Snargash Moonclaw]

Lots of cool stuff here guys, thanks!

Re: racial vision - depends on the system. AD&D (1-2e) IIRC gave elves ultravision & dwarves infravision. 3e did away with the terms (and the attempt at scientific rationalization) and referred to them as Low-light Vision and Dark Vision respectively. For my setting, using GURPS, I'm assigning Ultravision (literal UV sensitivity) to elves and infravision (also literal) to orkhs - interbreeding producing humans with normal vision. I haven't pinned down dwarves and halflings or gnomes as being a hybrid of the two like humans. GURPS Darkvision relies on "some means other than light, radar or sonar" with no attempt at explaining what. Hyperspectral vision ranges from UV to IR. Night Vision is simply a scalable reduction in the penalties imposed by poor lighting.

@Waldronate - I take it your comment about visual acuity vs field of vision among predators and prey implies you've read the CBG thread. I'm thinking of orkhs more along raptor lines as attached. Eyes are forward and nose bridge is minimal, providing much more binocular overlap, with the same peripheral scanning and movement detection. (I think their eyes would have to "bug out" slightly with the outer portion of the skull somewhat receded around the eyes - angling them back slightly.) Visual acuity in terms of detail is reduced - they make poor archers. Basically Paleolithic orkhs developed traits of both predator and prey - falling in a midrange on the food chain. (Of interesting note is Terrence McKenna's hypothesis that paleo/mesolithic humans may owe some success as a species to increased peripheral vision - resulting from consuming psilocybin - permitting them to hunt more effectively.)

Reduced UV would definitely result when only the orange-red sun is visible. Changes in ozone levels as a result of this would permit more of the UVA and B to reach the surface, but mitigating only slightly. Coupled with a protion of the visible light spectrum not being visible to elves could cause the entire race to suffer something along the lines of a 10,000 year collective case of Seasonal Affective Disorder. For any who care to read their ancient (meso-neolithic) history, this would actually explain a lot. It does warrant some slight revision of that document - incorporating the effects of Despair along with Pride, and probably having some influence on them during the 2nd (early Iron Age) Glacial Period. After the recurrence they would have identified the problem and now be considering plans to deal with/mitigate this when the next one comes around in another 15,000 years. (This is the equivalent of humans starting to plan for a major threat to the species in 1500 years, except that elves are psychologically more inclined to actually do so. . .)

I don't think taht UV or IR visibility would produce "colors" as such. While color (pigment) mixing and light mixing are different, I note that the artist's color wheel is complete. That is, the system is closed and colors blend consistently throughout the spectrum and back to the starting point on the wheel with no gaps, leaving no place where any additional hues might reside should a UV and/or IR sensitive artist seek to mix the additional color(s) on hir palette. Hence I'm inclined to expect these two perceptions to display some other characteristic - most likely producing radical alterations in shade/tint value and/or saturation of the visible colors as well as a slight spectral shift - the latter especially where the opposite end of the visible spectrum is opaque. Playing with the Hilbert Space below would be accomplished by extending one of the bottom corners while raising it's opposite and playing with the effect on the portion of polychromatic visible light below the central white locus where red and violet light mingle. I'm not sure what the extended portions would look lie - esp. for someone with hyperspectral vision extending both sides and adding a large new area across the entire bottom from the magenta section.

[waldronate]

By definition, a "color" is a light wavelength band. If you cannot detect a wavelength band then you cannot see that color. If your race can detect colors beyond human perception (IR and UV) then those wavebands would be perceived as additional colors and the race is likely to give them unique names.
The CIE chromaticity diagram you showed above is "full" only for a wavelength band between 380 and 700 nm (blue through red). The shape of the diagram was determined by asking volunteers to specify their perceptions of color and then determining the "typical" values. Thus, the diagram has three "corners" because humans have three waveband sensors. If your race has additional sensor types then the shape of the diagram will change.
As a practical application, consider that the color gamut (the displayable range of colors) for a typical CRT or print process is much smaller than the human visual response. TO see that this might mean, consider three races: humans, race RGB (has a visible range equivalent to the color gamut of a typical CRT), and race CMYK (has a visible range equivalent to the color gamut of a typical 4-color print process, or somewhat smaller than RGB). Humans can see many color differences that are invisible to both races CMYK and RGB. CMYK and RGB would not notice whole swaths of colors that humans could easily distinguish. RGB would be able to see some things that CMYK wouldn't be able to distinguish. Humans would find RGB art less satisfying than their own art because it has a much more limited range of colors and CMYK art less interesting still. Similarly, race RGB might see an uninteresting monochrome canvas when looking at a human painting of delightful shade of variations of saturated green.

I didn't read the CBG thread except at the first post, sorry.

CIE color space definition: http://en.wikipedia.org/wiki/CIE_1931_color_space
color gamut definition: http://en.wikipedia.org/wiki/Gamut
differences in color gamuts: http://dx.sheridan.com/advisor/cmyk_color.html