efilana Posted November 21, 2011 Share Posted November 21, 2011 Hello Forum! I am learning new techniques now and realized that I have no idea what to do with Shadow Channel. I have this basic rendering which I want to improve with textures in PS. I did water and grass and those came out nicely, but now I need to work with my shadows. I have them rendered as a channel (Maxwell), but I have no idea what to do with that b/w image. Can anyone give me a link or explain to me the work flow? Thank you very much! Link to comment Share on other sites More sharing options...
LordRaven Posted November 21, 2011 Share Posted November 21, 2011 Here is a short tutorial on how to work with render elements in photoshop: http://www.cgdigest.com/vray-render-elements/ Hope it helps. Link to comment Share on other sites More sharing options...
efilana Posted November 21, 2011 Author Share Posted November 21, 2011 Hi Alex, thanks for the link - it is useful itself. And I think it is time for me to switch to Vray Anyways, Maxwell Shadow channel look very different, I attached image of it. [ATTACH=CONFIG]45835[/ATTACH] Link to comment Share on other sites More sharing options...
Brodie Geers Posted November 21, 2011 Share Posted November 21, 2011 You can use it for anything of course but it's typically looked at differently in Maxwell than it would be in Vray for example. In Maxwell you already have the shadows embedded in your render which are physically accurate. So the primary purpose isn't really for tweaking your shadows to make them less accurate (although you can do that of course). It's primarily for replacing an object/material in post. For example, often render my grass as a plane with a grass texture on it. Then in post I'll replace that with some photo grass. I'll check the Shadow channel in the grass material and run a shadow pass which I can then overlay on top of my photo grass to get the shadows back. That's why in Maxwell you have to check the Shadow channel for each material you want the shadows to fall on in the shadow pass (they only anticipate you needing it for 1 or 2 materials at a time as opposed to wanting a shadow pass with ALL of your shadows). You can also create a sort of ambient occlusion pass as described here ( http://www.youtube.com/user/MaxwellRenderLabs#p/a/1FE393A926FF8A17/1/rSV0blQxFq8 ). However it's limited in that you can't very well control the falloff of the shadows. -Brodie Link to comment Share on other sites More sharing options...
efilana Posted November 21, 2011 Author Share Posted November 21, 2011 Brodie, I read the Maxwell manual (don't laugh) and applied Shadow Channel using multiply to my base image. I was very happy with the result. I have one more question: how do you deal with the shadows being black? transparency? Link to comment Share on other sites More sharing options...
Brodie Geers Posted November 21, 2011 Share Posted November 21, 2011 Brodie, I read the Maxwell manual (don't laugh) and applied Shadow Channel using multiply to my base image. I was very happy with the result. I have one more question: how do you deal with the shadows being black? transparency? The Maxwell manual is invaluable. I still consult it on a fairly regular basis. I have a printed copy but now I often just go to the PDF and do a word search for what I'm after. It's a great manual. The shadow channel will be in grayscale. Based on your image it looks like you probably just have a strong sun creating all your light so you're getting that very sharp black to white. If you check that link though, you'll see that the shadows will match up with whatever emitters you have in the scene. If you use mulitlight you can get a separate channel for each light (be sure and choose Output Mode as Separate in the Channels dialogue). Then if you use skydome, or an hdri, you'll see some softer shadows with gray tones. You could also do what they did in the video which is to create a polygonal emitter placed some distance from the scene and use it as your sun which can provide softer shadows. The problem I often have is that real shadows as created in the main render pass aren't usually gray but have some slight tone to them so if you're matching your shadows to Maxwell shadows it might take some extra tweaking beyond just a multiply layer. If you like the result of placing your shadow channel on a multiply layer then there's nothing wrong with that. Just make sure you understand what that means. You're creating a physically inaccurate result by doubling the darkness of your shadows but maintaining the same sun level and value of your highlights. As I say, nothing wrong with that but you'll be providing a more stylized look. It would be a bit akin to using the burn tool set to shadows and going over your shadow areas with that in order to darken them. It's a common method to provide some contrast but one must be careful in using it. -Brodie Link to comment Share on other sites More sharing options...
efilana Posted November 22, 2011 Author Share Posted November 22, 2011 Thank you, Brodie, you answer is very thorough. I think that working with shadows tone is rather small task comparing to other things that we go through with post production. Thank you you again, you also answered my unasked questions, for what I am grateful. Regarding the video from the link - how did they do this really cool grass and road there, do you know? Link to comment Share on other sites More sharing options...
Brodie Geers Posted November 22, 2011 Share Posted November 22, 2011 I had heard about that particular scene but it's been quite awhile. As I recall they used a photo with that grassy image and then used Camera Projection to map that photo onto the ground plane. So if you moved the camera at all the ground plane texture would look very distorted but from that one perspective it matches perfectly and you get the shadows from the building to fall onto the ground plane. -Brodie Link to comment Share on other sites More sharing options...
efilana Posted November 22, 2011 Author Share Posted November 22, 2011 Thanks, Brodie. That makes sense. And looks very good. I am trying to learn how to make nice grass, unsuccessfully so far. Link to comment Share on other sites More sharing options...
Brodie Geers Posted November 22, 2011 Share Posted November 22, 2011 Well, depending on what modeling program you use Maxwell just came out with ver. 2.6 which now includes hair. I haven't tried it yet but for awhile that seemed to be the method of choice for good grass. Might be worth a shot. I'm hoping to try it soon. -Brodie Link to comment Share on other sites More sharing options...
efilana Posted December 2, 2011 Author Share Posted December 2, 2011 Brodie, I wanted to show you what I have done. I really appreciate your help and advices. I know it is far from perfect, but it is my first attempt. Link to comment Share on other sites More sharing options...
Brodie Geers Posted December 2, 2011 Share Posted December 2, 2011 Looks pretty good. Thanks for reporting back. Nice image -Brodie Link to comment Share on other sites More sharing options...
efilana Posted December 2, 2011 Author Share Posted December 2, 2011 Thanks, Brodie. There is always room for improvement. Nice hair, btw Link to comment Share on other sites More sharing options...
Brodie Geers Posted December 2, 2011 Share Posted December 2, 2011 Nice hair, btw eh? -Brodie Link to comment Share on other sites More sharing options...
efilana Posted December 2, 2011 Author Share Posted December 2, 2011 Yours. Saw your pic on FB Link to comment Share on other sites More sharing options...
Brodie Geers Posted December 2, 2011 Share Posted December 2, 2011 awww. haha. Well thanks It's changed a couple times since then I believe. -Brodie Link to comment Share on other sites More sharing options...
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