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Shed

Lighting Issues

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Hi there,

I'm building a street scene that is lit using an image in the luminance channel as a sky object. I'm using the physical render in R13. It works fine and gives me the the result I'm looking for, all good!

However, I want to add some street lights. When I add spotlights, the scene darkens as if this is the only light in the scene, and if I use a luminance texture the light doesn't seem to be strong enough or light surrounding objects as I expect.

I'm guessing you can't use both global illumination to light a scene and standard lights together, but could someone clarify this for me.

Cheers

Steve

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I think you should be able to use the normal 3D lights with GI, but I'm not the best guy to answer you.

Are you using an HDR image as your light source?

I'm thinking it could be that your scene works just fine with the data from 0 to 1 on the luma channel, but with the normal lights added, their values could be higher than 1.

That would mean the HDR you use should have values greater than 1 to solve an accurate lighting solution.

Then again I'm just guestimating here, so somebody wiser please correct me.

Possible to try the scene file on my end to see if it's a problem on your machine alone?

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using normal lighting should help GI not stop it working.

lights should mean your scene renders fast then without them.

like Happyrender said post your scene file

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Cheers for response.

You're right, the texture in sky object is a .hdri file. I kindda get what you mean about the light values, but i'm not sure what to do with this info!

I've attached a cut down version of the scene file, all the textures are missing except the relevant files (too big otherwise). The lights in the flats use a sun texture from the gsg hdri kit. I know this is odd, but it was the only way I could get the lights to work in the scene. sure this can't be right!

I'm looking to get natural sunlight, but I also want to add additional fill lights and street lamps. Let me know if you have more luck ;)

too big to upload to the site, the hdri file is 10mb!

https://dl.dropbox.com/u/22598919/street.zip

Thanks again

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You need to go into your illumination tab and bump up the GI Strength. This is located in your texture at the bottom of the checkboxes...

post-139996-0-52808800-1346793626_thumb.

post-139996-0-11218700-1346793629_thumb.

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Cool, how do get such soft edges on your lights?

Is this essentially making the illumination channel brighter than 100% on a texture by texture bases? This is pretty handy to know as often I feel the GI comes out a little dark and I have to brighten in post.

I've been playing a bit more and I've realised that when I add a new light to my scene, everything darkens (as if switching from default lighting). However, when I render, it is still using the GI and the c4d light. Is there a preview setting I need to change to get a more accurate preview as it's hard to work when everything is black!

Lots of questions ;) But is this how you would go about building an outdoor scene with natural lighting. You wondered if I was going about it the right way.

Thanks again

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The reason the scene turns black is because of the lights. Simply turn the editor "Traffic light" off in the object manager for every light. This way it renders but doesn't show in your scene. As for the GI it is by texture basis. The lights are spot lights just as you had it but the shadow is set to area and the light is shown as a visible setting of "volumetrics." Not exactly straight forward stuff but look in the light setting in the general tab and you should be able to find it. The visible light area also has to be toggled by handles on the light after you have set it. Glad I can help. Being unemployed I need to keep my mind occupied til that sorts out. Let me know if you have any other ?'s

post-139996-0-07938300-1346817568_thumb.

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I'm sorry to here that. I know how you feel, it's not much fun! But something will turn up soon ;) Are you a 3D artist by trade?

Cheers for your help again. I do have one other question actually! With spot lights the light source always comes from a tiny pin point. I thought this would be controlled by the 'area shape' menu under details, but this never seems to do anything! Do you know a way to change the source lights shape/size?

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You can make the spot circular, elliptical, square or rectangular. You can avoid the "point" effect using clipping.

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