A camera films a 3D character which walks from right to left across the screen; underneath is a ground-plane.
When rendering, I have two render layers; one is the 3D character with all usual passes, 2nd is the ground plane which basically only fetches the AO. So I only have the AO from the character solo, which works well enough as a shadow for this scene.
Now while comping I saw that I might not get around rendering a reflection of this character. So basically, I simply want to have the reflection on the ground plane, and render this alone (beauty+alpha should be sufficiant; Alpha from the character, not the ground plane).
In my ground-render layer, I just enabled Reflection but this gives me some weird super-low res result, It’s like 20px wide but blown up to HD, very weird.
I’m not really good with Blender, so I have no idea how to set this up right flipping it upside down in the comp won’t work though, because of the perspective …
Big big big problem in Blender.) Because there is now shadowMaterial with glossy you can use this 3 pass method and instead of only using diffuse node for shadow add a glossy node to it. So you have 1st pass your charakter. 2nd pass floor geometry white with reflection and shadow. 3rd pass floor geometry pure white. In comp put it together like described here.
A .blend for download you can find in the description from the vid.
In Autodesk VRED for example you can do it in 1 pass with shadow material. Simply enable glossy reflection in shadow material .
Big big big problem in Blender.) Because there is now ShadowMaterial with glossy. U can use this 3 pass method and instead of only using diffuse node for shadow add a glossy node to it. So you have 1st pass your charakter. 2nd pass floor geometry white with reflection and shadow. 3rd pass floor geometry pure white. In comp put it together like described here.
A .blend for download you can find in the description from the vid.
In Autodesk VRED for example you can do in 1 pass.
There is a shadow pass option in Blender Cycles, but you are required to use lights rather than emitting surfaces or the World to produce the shadows. If you need to create shadows from, say, an HDRI image mapped to the World, then you’d need this technique. But if you’re using a standard Sun lamp, for instance, it’s super-quick to set up:
So the dinosaur wals this plane. From the plane I only need the AO for shadows (that works well enough in the scene, it’s super overcast). What I need is simply a mirror from this ground plane. So the dinosaur, as it is on top, one time upside down on the ground, but with Alpha etc
From your screenshot, it seems to only adress shadows, but I have every shadow I need. I really only need a reflection, and I can’t to get how to set that up
Hi sasa42,
I watched the video, but it doesn’t seem to adress for ground reflections, did I get something wrong? I see the very diffused spill on the ground, which is not what I’m after
What I thought of now is to simply totate the camera 180°, or the Dinosaur. IO’ll try of that works…
Ok guys I tried flipping the model, and that kinda worked. What I forgot is that a mirror also… mirrors the image so of course I have to adjust for that. I tried setting the X-scale to -1 and that actually worked, BUT when the character walks I get some weird deformation in its feet. When standing it’s fine, not when walking. Somehow it feels like some part of the whoe construct can’t be scaled that way, damn.
As with all reflection passes I’ve ever worked with, the reflection doesn’t use Alpha; rather, it is over Black. You simply Screen the reflection pass over your background plate.
If your dinosaur were walking on water, you can add a displacement modifier and/or bump map and your reflections will be distorted appropriately.
flipping it upside down in the comp won’t work though, because of the perspective … 
so of course I have to adjust for that. I tried setting the X-scale to -1 and that actually worked, BUT when the character walks I get some weird deformation in its feet. When standing it’s fine, not when walking. Somehow it feels like some part of the whoe construct can’t be scaled that way, damn.
