Reqiest║Metal temperature

[fused]

haha ^^
indigo is awesome. beat that maxwell!

Code: Select all

    <material>
        <name>0_mid0</name>
        <phong>
            <ior>1.010000</ior>
            <diffuse_albedo>
                <constant>
                    <rgb>
                        <rgb>0.800000 0.800000 0.800000</rgb>
                        <gamma>2.200000</gamma>
                    </rgb>
                </constant>
            </diffuse_albedo>
            <exponent>
                <constant>1000.000000</constant>
            </exponent>
            <base_emission>
                <constant>
                    <uniform>
                        <value>1.000000</value>
                    </uniform>
                </constant>
            </base_emission>
            <layer>0</layer>
            <texture>
                <uv_set>default</uv_set>
                <path>C:\Users\Yves\Desktop\spectrum.png</path>
                <a>0.0</a>
                <b>1.0</b>
                <c>0.0</c>
                <exponent>1.0</exponent>
            </texture>
            <emission>
                <shader>
                    <shader>
                        <![CDATA[
def Vec3ToReal(vec3 v) real : ((doti(v) + dotj(v) + dotk(v)) / 3.0)
#indigos wl range is 400 - 700 nm. tial & error ftw
def eval(real wavelen, vec3 pos) real: Vec3ToReal(sample2DTextureVec3(0, vec2((wavelen - 400.0) / 300.0, 0.5)))
]]>
</shader>
                </shader>
            </emission>
        </phong>
    </material>

edit: hehe i know this is not how a normal lamp emission spectrum would look like but i only have paint ^^

[pixie]

OMG Fused, what have you done!!!?

[fused]

i just reproduced something in ISL that you could just do with a tabulated spectrum. what a waste of time lol

[fused]

high pressure sodium lamp:

real:

indigo:

hps.png (299.17 KiB) Viewed 3175 times

purespider kindly helped me out with photoshop

[lycium]

ahhh, that wonderful warm glow of an HPS lamp

cool stuff!

[pixie]

i just reproduced something in ISL that you could just do with a tabulated spectrum. what a waste of time lol

Anytime soon I won't have any more time to waste... Life was so much fun while poking with numbers back and forth, messing on raw xml... those days are gone now, and whose the blame? Yours fused, yours! You wicked!

[dougal2]

I lifted all the measured spectra as used in the LuxRender source and included them as presets in my working copy of blendigo. I had to do some basic linear-interpolation on the data to fit it to the 400-700nm range, but it seems to look reasonably accurate.

I will have to do some careful reading in order to establish whether the CCL3-by licensed spectrum data can be included in the GPL exporter and released.

[Jambert]

impressive

I don'tunderstand exactly how it works but congrats all. Could it be mix with ies?

[dougal2]

impressive

I don'tunderstand exactly how it works but congrats all. Could it be mix with ies?

Yes, they can be used with IES. The way I've implemented it is as an alternative to RGB or Blackbody for the emission spectrum. (Basically, a load of named presets for regular-tabulated data).

[dougal2]

I will have to do some careful reading in order to establish whether the CCL3-by licensed spectrum data can be included in the GPL exporter and released.

As far as I now understand, this is permissible - unless anyone would like to correct me, these presets will be included in Blendigo after 2.2 stable.

[Jambert]

realy good to know, thx

(still don't understand everything because of my poooooor english )

[OnoSendai]

I will have to do some careful reading in order to establish whether the CCL3-by licensed spectrum data can be included in the GPL exporter and released.

As far as I now understand, this is permissible - unless anyone would like to correct me, these presets will be included in Blendigo after 2.2 stable.

Wow, cool stuff Doug!

[neo0.]

Well.. to be honest, Im kind of confused when it comes to this.. is light temp (in kelvins) equate to the same colors as metal temperature? Obviously, it would vary with different metals, but maybe it is similar for a few?

There is no such thing as "metal temperature" in the way you are using the term.

When you heat a metal, or another material, it emits a black body spectrum ("light temperature"), which depends on the temperature.

Now, if you excite a metal atom, it will emit a photon at a characteristic wavelength upon relaxation. C.f. http://www.meta-synthesis.com/webbook/1 ... photo.html
That's the effect you see in sodium-vapour lamps (street lamps) and in fireworks.

So, as Lyc mentioned, you just need to find the emission spectrum for the metal you want, and use it.

But aren't the various components in fireworks heated to the same temp in spite of their different composition? So the same temp produces a different color?

[CTZn]

Combustion and heating are two distinct processes, in the former case I think that metallic ions are in cause for the hue (also the reacting materials are transformed).

Wow fused, I was expecting some more code to achieve this, pretty amazing !

That should be documented as an ISL technique before it fades into oblivion. It's nice, simple and usefull.

All your fault again, neo0.

[neo0.]

Wow, to to be honest the physics of this is a little beyond me.. Im just looking fot a way to make it more artists friendly.