External background settings

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Jay-ko
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External background settings

Post by Jay-ko » Sat Feb 02, 2013 6:04 am

Is that possible to do something like that?

<background_settings>
<background_material>
<include><pathname>background.igm</pathname></include>
</background_material>
<emission_scale>
<material_name>background_material</material_name>
<measure>luminance</measure>
<value>1000</value>
</emission_scale>
</background_settings>

because i dont find where to fix that:

Image
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Jay-ko
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Location: Paris

Re: External background settings

Post by Jay-ko » Sat Feb 02, 2013 7:04 am

My background.igm is something like this:

Code: Select all

<?xml version="1.0" encoding="UTF-8" ?>
<scenedata>
    <material>
        <name>background_material</name>
        <diffuse>
			<texture>
                <uv_set_index>0</uv_set_index>
                <path>overcast.exr</path>
                <exponent>1</exponent>
                <a>0.0</a>
                <b>1.0</b>
                <c>0.0</c>
                <smooth>false</smooth>
		
<tex_coord_generation>
			<spherical>
				<rotation>
					<axis_rotation>
					<axis>0 0 1</axis>
					<angle>0</angle>
					</axis_rotation>
				</rotation>
			</spherical>
</tex_coord_generation>
			</texture>
<albedo>
<constant>
	<rgb>
	<rgb>0.0000 0.0000 0.0000</rgb>
	<gamma>2.2</gamma>
	</rgb>
</constant>
</albedo>

<base_emission>
	<constant>
	<regular_tabulated>
		<start_wavelength>xxx</start_wavelength>
		<end_wavelength>xxx</end_wavelength>
		<num_values>xx</num_values>
<values>
xxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxx
</values>
			</regular_tabulated>
			</constant>
</base_emission>

<base_emission>
	<texture>
		<texture_index>0</texture_index>
	</texture>
</base_emission>
	<emission_scale>
					<material_name>background_material</material_name>
					<measure>luminance</measure>
					<value>1000</value>
	</emission_scale>

  </diffuse>
</material>
I think "emission_scale" is the seed of the problem but i don't know why
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CTZn
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Re: External background settings

Post by CTZn » Sat Feb 02, 2013 8:14 am

Include statements must be at the <scene> root level. Move it before the background settings.

Possibly a solution might then be to add an UID tag to the linked igm material with a random value, and use that value within a <material_UID> (hopefully) tag in place of the include currently.

I'm not sure if I'm making sense, I'm a bit late on the topic of UID's management.
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Jay-ko
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Re: External background settings

Post by Jay-ko » Mon Feb 11, 2013 11:24 pm

i think i'm passing up something...
For several reasons i use maxigo and i cant' use "Indigo for 3ds max" in my case. (and i prefer render in indigo)


So look at this, it seem correct no?:

Image

in "instance" with this:

Image

My sky background material is the same i have describe here... and my result is i have a black no emiting sky...
And i don't find any help with the manual on it.

So i'm quite disapointed... even when i pick the material inn indigo, and i setup manually the background setting i obtain a sort of material overide grey scene with ambiant occlusion... and i just don't understand waht is going on? :)
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Jay-ko
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Re: External background settings

Post by Jay-ko » Mon Feb 11, 2013 11:37 pm

Perhaps i'm totally in wrong but... when i use a simply environement sky, i need to setup my exposition like that:


Image
Image


But for me, a nice couple of exposition values for an exterior daylighting scene is aprox 8 or 9 ev for a 250 iso.
And wikipedia learn to me that an overcast sky is about 10000 lux... so if you can explain to me why it's not like in real world i'll be very happy :)
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fused
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Re: External background settings

Post by fused » Tue Feb 12, 2013 12:30 am

Jay-ko wrote:Perhaps i'm totally in wrong but... when i use a simply environement sky, i need to setup my exposition like that:


Image
Image


But for me, a nice couple of exposition values for an exterior daylighting scene is aprox 8 or 9 ev for a 250 iso.
And wikipedia learn to me that an overcast sky is about 10000 lux... so if you can explain to me why it's not like in real world i'll be very happy :)
Hi Jay-ko,

It also depends on the camera exposure time and size of the aperture (fStop). The shorter the exposure time the lower the needed ISO and/or EV adjust.

Sunny 16 rule: On a sunny day and with ISO 100 film / setting in the camera, one sets the aperture to f/16 and the shutter speed to 1/100.

Works as expected with Indigo's sun/sky model.

Edit: didn't see that you were talking about an environment map as bright as an overcast sky. In that case the sunny 16 rule doesn't exaclty apply but is still a good rule of thumb.

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Jay-ko
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Location: Paris

Re: External background settings

Post by Jay-ko » Tue Feb 12, 2013 11:03 pm

Thank you for that Fused!
i use this exr picture on a half sphere:
Image
like this:
Image
the material is setuped like this:
Image
(same intance in diffuse an emission)
i obtain this:
Image
i have this parameters:
Image
Image

of course by default i have 1/100 speed aperture. (thank you for your reply)

Is that a correct way to build an environement?
If i use a sunny exr, i'll obtain really dense shadows?
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CTZn
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Re: External background settings

Post by CTZn » Wed Feb 13, 2013 2:58 am

Your setup is not optimal.

You should not need to use a geometry as environment, delete/hide the half sphere. If a material is defined as background then Indigo will use its own environment system with it.

Also such materials take no diffuse component; Indigo will ignore it.

About crisp shadows: this topic has been raised several times, it comes down to good dynamic ranges from the env maps.
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Jay-ko
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Location: Paris

Re: External background settings

Post by Jay-ko » Wed Feb 13, 2013 3:31 am

hummm interesting...

To be honnest i used an half sphere because i need to turn and move the environnement on Z with a visual return in 3ds max.

I know i can turn on Z axis in Indigo, but i don't understand how to move on Z. Perhaps i don't see where is the parameters.
Maybe i can script it in the external background settings in the "<tex_coord_generation>"?

Thank you a lot for your time.
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CTZn
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Re: External background settings

Post by CTZn » Wed Feb 13, 2013 3:43 am

Jay-ko wrote:Perhaps i don't see where is the parameters.
Maybe i can script it in the external background settings in the "<tex_coord_generation>"?
You can write the rotation in the XML, just be aware that it is expressed in radians.

However I'm sure that you will find a map rotation parameter in the proper maxigo section.
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Jay-ko
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Re: External background settings

Post by Jay-ko » Wed Feb 13, 2013 6:59 am

I just try without diffuse, and of course that work fine.

So i try to use this material in external environement:

Image

And when i try to render it i have that:

Image

So i try to setup the environnement picture in indigo itself; but it's not exactly the same "spectrum" (it's blueish than 3ds max export)
Image

And unfortunatly i can't " Image "

So i try to make my own env material (like the one at the begginning of this thread)
for this i use the one how work fine.

but when i render it's do that:
Image
And there you have my reason why i want to make my own external background xml file.

Now the "only" way to produce a picture is "as you say "not optimal". And 'm totally agree whith that.

I wrote all this stuff because, when you say me at the beggining, "include must be at the <scene> root level" i don't know where need to copy/paste the correct caracter chain between my settings.igs and my scene.igs

i can isolate my include for my env.igm
i can copy paste juste under <scene>
i can save the files and re open the scene one.

But here, i have this:
Image

and there... i just want to broke everything just near me and eat my hat :D

(sorry for my bad english)
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Zom-B
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Re: External background settings

Post by Zom-B » Wed Feb 13, 2013 7:53 am

polygonmanufaktur.de

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Jay-ko
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Re: External background settings

Post by Jay-ko » Thu Feb 02, 2017 3:37 am

Just to close correctly this topic.

This is totally possible.


Use the .igs created by the exporter and open this file as xml to copy paste what do you keep to keep

Just remerber to keep "<scenedata>..</scenedata>" instead of "<scene>..</scene>".

Feel free to ask if needed.
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