what's wrong with my render? shadows problem
I was trying to follow this tutorial for working on my lighted scenes
http://area.autodesk.com/tutorials/rendering_a_quick_realistic_scene_with_mental_rays_final_gather
But mine doesn't look quite like that. I have some strange shadows and artifacts if I'm using that term right. I could use some help fixing them.
http://area.autodesk.com/tutorials/rendering_a_quick_realistic_scene_with_mental_rays_final_gather
But mine doesn't look quite like that. I have some strange shadows and artifacts if I'm using that term right. I could use some help fixing them.
Replies
Try enabling Raytraced Shadows instead, and fiddle with the settings.
Edit : Gah !
To fix it I just recreate the lights. I think there are some settings added to the lights you can turn on. There might be some scripts available to convert them over also.
Just turn off shadow casting for the light, make it an area light and make sure final gather is on. You can then tweak the "samples" setting in the Light attributes to get more detail out of the area shadows.
Once your happy with your lighting go lookup information on mia_material.
If your interested in learning more about mental ray also check out http://mentalraytips.blogspot.com/
I just wish I could follow that tutorial and get that clean look
Use a spot light instead and keep your cone focused tightly on the model, this will better suit your needs and you won't need as many samples to get good smooth shadows.
Either that, or use retraced shadows as been mentioned above.
To explain this point: Imagine a shadow map is an image of the shadows in your scene (not the case but easy to visualise) When you use a distant light with shadow maps the light effects the whole scene so to do the shadows it must draw the whole scene in its shadow map. so that massive plane is enlarging the scene and wasting resolution. using a spotlight means the map only has to be drawn for the area within the cone meaning you map covers a much smaller area and will appear much sharper.
TBH though I never use shadow maps unless im doing hair.
1. Create a directional light.
2. Turn on raytrace shadows for your directional light.
3. Open render globals and turn on mental ray.
4. Go to the quality tab and select "Production."
5. Go to the indirect lighting tab and click the tick box for final gathering.
6. In the indirect lighting tab under environment click on "Image Based Lighting> Create"
7. A new window appears for the sky dome, set the type to texture instead of image and then click on the colour swatch and make that whatever colour you want, in that tutorial it's a light blue colour.
8. Render your scene it should be exactly what you want. From there you can tweak the colour of your sky dome, the colour and intensity of your light, and the colour of your light's shadows. I'd avoid shadow colour though and use your sky dome to tint the shadow to the desired colour just like it works in real life.
Also if your looking for good results its a good idea to use a HDR rather than just a colour swatch. your loosing so much potential if you just use 1 colour. IBL was invented to simulate the lighting of a specific place using photos of it.
you can get some HDRs here:
http://www.yboo.net/hdri/
http://www.hdrmill.com/Freebies.htm
http://www.crazy8studio.com/hdr.php [the best of the lot]
Another thing to do is to go into your directional lights 'raytrace shadow attributes' and set the light angle to something like 2 or 3 and the shadow rays to something like 32.
Without this your shadow is hard. adding to the light angle with soften the shadows more. softening the shadows needs more samples because of the noise softening introduces. so get the softness to a value you like and then increase the samples till you get it looking clean.
so far as the environment goes a ramp is fine. you get some variation in that. a flat colour is pointless though. your loosing a massive amount of potential for no reason what so ever. I dont disagrees about environments if you have surrounding geometry and local colour information your sorted. If your rendering something on its own on a plane you gain a massive amount by using a probe.