Custom shadow projection in Vray

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5 Mar, 2012 gus_ann
5 Mar, 2012 # Re: Custom shadow projection in Vray
Hello, flipping through Internet pages stumbled on a picture wall as pawns on the queen. Please tell me how to do it with help Vray? Used here is the shadow of the card or a mask?


5 Mar, 2012 Anton (Staff Author)
5 Mar, 2012 # Re: Custom shadow projection in Vray
Hello! This can be done as you wish. To give any specific comments, you need to see the image in question😉


5 Mar, 2012 gus_ann
5 Mar, 2012 # Re: Custom shadow projection in Vray
Here is an exemplary picture of what should happen


5 Mar, 2012 Anton (Staff Author)
5 Mar, 2012 # Re: Custom shadow projection in Vray
This is done in Photoshop. Doing this in 3d, to static visualization (not animated) by projecting light from the card Projector Map / Use texture, etc., on a flat wall - does not make sense.


5 Mar, 2012 gus_ann
5 Mar, 2012 # Re: Custom shadow projection in Vray
Thanks for the reply, it was interesting to learn how to do things. Tell me, why it does not make sense?


5 Mar, 2012 gus_ann
5 Mar, 2012 # Re: Custom shadow projection in Vray
Tell me, why then exists the shadow map and when it should be applied?


5 Mar, 2012 Anton (Staff Author)
5 Mar, 2012 # Re: Custom shadow projection in Vray

Because in this particular example, to impose such a shadow in Photoshop on a flat wall, it takes no more than a couple of minutes. To do this, it will be enough to take the desired silhouette, slightly blur it around the edges and apply a little transparency to the wall. So you will get the effect you need.

If you do this in 3d, then you also have to look for such a silhouette, just have to blur its edges, then to put it as a searchlight card for the light source.
Then to direct this light source to the wall, to select its intensity, the dimensions of the searchlight and to exclude from its illumination and shading all objects except the wall and, possibly, the chess board (floor). Then do a bunch of test renders, and adjust its parameters and position to achieve the desired effect. To the shadow was the desired density, located in the right place, etc. This will take a couple of minutes ... but for what? For the sake of "sports principle" do it in 3d?

So you can only burn time with nothing to do.

An exception is the situation when the shadow of the required form should fall not on a flat wall, but on a set of objects of a scene, repeating their contours and realistically "streaming" along their surface. Here in this case, to make such an effect, with the help of post-processing render, will be either very problematic or not possible in principle.

If it's interesting to know how these things are done and you are not described enough, at the very beginning of my post, steps, then lay out your render, the silhouette of the desired shadow and I will show you, with a concrete example, how it is done in Photoshop.

If you have a more difficult situation, that is, the shadow should not fall on a flat wall, but on the objects of the scene, then just lay out your render so that we can see what is going on and give you specific recommendations😉



5 Mar, 2012 gus_ann
11 Mar, 2012 # Re: Custom shadow projection in Vray
I did not have a particular scene, quickly sketched here, sorry if not quality - I'm just learning. Here is an example of what should happen: My rendering with shadow: Render without shadows: And the silhouette: Of course as a student I'm interested in all possible versions, but let's look at that first with photoshop. Anton, I ask you to describe all the action steps, as photoshop know very roughly. Thank you in advance. PS: The first picture - that's not what I did - this is a pattern that I want to do but do not know how !!! That's why even ask to explain how to do this in Photoshop😁


5 Mar, 2012 Anton (Staff Author)
12 Mar, 2012 # Re: Custom shadow projection in Vray

Hello!

Describing the detailed work, in fact, with the tools of Photoshop, goes beyond the scope of our resource, therefore, I'll just stage-by-stage show what to do. That is, the reception itself, how to change the shadow. But with what tools, this is done, you have to study on your own, if you have not dealt with this program yet. The benefit of the lessons and resources devoted to working with Photoshop in principle, and the methods of photomontage (compositing) in particular - a lot of 🙂

So:

1 - We throw in Photoshop a file with a shadow. In it, on a new layer, we throw the file without it.
In principle, you can simply take a render without a shadow, but then you have to paint the shadow under the pawn itself, so that it does not "hang in the air", but stood, which is not rational at all.

2 - Now, the second layer, where the render with the shadow, is rubbed so that the bottom of the pawn was with the shadow, but at the same time, the silhouette of the pawn was removed from the white wall:

Or, in other words, erase the shadow silhouette of the pawn.

3 - Then, similarly to the shadow layer, in the same file we put a file with the silhouette of the queen, on the new, third layer, where the first layer is a render without a shadow, the second is a render with a shadow.

4 - We erase the white background around the silhouette, so that only the black silhouette remains:



5 - Now we scale and place this carved out silhouette of the queen, in the place where the silhouette of the pawn used to be. Scale, proportions and position, choose according to taste / according to the conditions of the task:


6 - That's practically all. Now it's just a little bit 🙂
The scaled and positioned silhouette of the shadow needs only to be blurred slightly to make it look like a shadow, not a picture on the wall:

Again, everything "by sight". As more like.

7 - The last thing to look out for is the shadow in the horizontal plane on which the pawn stands. Firstly, it is very clear (this is a rendering issue), and secondly, it is slightly smaller than the base of the queen, and it should be slightly painted in the lower zone to the right. To horizontal shade, clearly aligned with the vertical:

How to do it, the options are the sea. I, for example, just drew it by hand, with a black brush.

If there are no other requirements for the shadow, then in principle this is all. Approximately so, compositing of the necessary image from three others is done.

In a good way, the silhouette of the queen should not only be positioned and scaled, but also slightly bent her lower part, according to the oblique line connecting the horizontal plane (floor) and the vertical (white wall). Also, it would be appropriate to add a bit of dirt and roughness to them, etc ..:

But, as is rumored, this is a completely different story ...😁



5 Mar, 2012 gus_ann
12 Mar, 2012 # Re: Custom shadow projection in Vray
Thank you, we will try and learn.


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