New online technical reference

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OnoSendai
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New online technical reference

Post by OnoSendai » Tue Jun 30, 2015 2:21 am

We're in the process of moving the technical reference from a PDF file to a more accessible version:

http://indigorenderer.com/indigo-technical-reference

I have updated the ISL documentation a bit, there are some pretty pictures here:
http://indigorenderer.com/indigo-techni ... oise-funct

and here:

http://indigorenderer.com/indigo-techni ... oise-fun-0

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Zom-B
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Re: New online technical reference

Post by Zom-B » Tue Jun 30, 2015 9:37 pm

A good move to put this into the web.
Example renders are also very welcome :)
polygonmanufaktur.de

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Headroom
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Re: New online technical reference

Post by Headroom » Thu Jul 02, 2015 11:52 am

Great idea!
Perhaps the document could also use an update on the content, not just here format and where it is located. The PDF is from 2011 so not exactly current. A good question to contemplate may be who is the target audience for the reference.
Most recently I've been struggling with two things and unfortunately the reference came up short in helping me answer my questions:

1. I wanted to know what technical unit is used for a tabulated emission spectrum for a light source. An example for such a light source would be the blue LED in the material database. I have a workaround in using normalized data for the tabulated values and then applying an emission scale, say in Lumen.
I still don't have an answer to that question.

2. This actually led me to investigate how lightlayers can be adjusted and exported correctly from Blendigo as that does not work when you have emission scale enabled in Blendigo. That question you was actually answered by Ono in an online chat.

Exporter writers are clearly in need of a good reference document.

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Re: New online technical reference

Post by OnoSendai » Thu Jul 02, 2015 12:07 pm

Headroom wrote:Great idea!

1. I wanted to know what technical unit is used for a tabulated emission spectrum for a light source. An example for such a light source would be the blue LED in the material database. I have a workaround in using normalized data for the tabulated values and then applying an emission scale, say in Lumen.
I still don't have an answer to that question.
It's spectral radiance, Wsr^-1m^-3

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Headroom
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Re: New online technical reference

Post by Headroom » Thu Jul 02, 2015 11:01 pm

Thank you very much!
I thought that's what it should be but was not sure.

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Re: New online technical reference

Post by CTZn » Thu Jul 02, 2015 11:43 pm

Agreed, nice move 8)

Ah meanCurvature(), I've been looking for this one !

Voronoï cells having a value of zero at contact edges would be a useful type.
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Re: New online technical reference

Post by OnoSendai » Thu Jul 02, 2015 11:49 pm

CTZn wrote:Voronoï cells having a value of zero at contact edges would be a useful type.
You could detect this by taking a sample in each direction and checking the second derivative of distance to the nearest voronoi site with finite differences.

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CTZn
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Re: New online technical reference

Post by CTZn » Fri Jul 03, 2015 12:21 am

OnoSendai wrote:
CTZn wrote:Voronoï cells having a value of zero at contact edges would be a useful type.
You could detect this by taking a sample in each direction and checking the second derivative of distance to the nearest voronoi site with finite differences.
Exactly, that's why I can't :D (e: galinette taught us iirc)

I mentionned otherwhere that albeit I know how I would use them, I am not able to implement finite element methods myself :/
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Re: New online technical reference

Post by OnoSendai » Fri Jul 03, 2015 12:27 am

have a look at https://en.wikipedia.org/wiki/Finite_difference, "Higher-order differences"

so the code would look something like

second_deriv = voronoiDist(p + vec2(h, 0)) - 2*voronoiDist(p) + voronoiDist(p - vec2(h, 0))

where h is a small value (like 0.0001)

which would get the second derivative (curvature) in the x direction.

What it's doing is comparing the average of the two voronoiDist values to the left and right of our point p, with the value at p. If the average is bigger then it's positive curvature, if smaller, it's negative curvature, if it's the same, it's flat.

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Re: New online technical reference

Post by CTZn » Fri Jul 03, 2015 1:26 am

Well I will have to try this now that you made it seem affordable to me, thanks a lot Ono !
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