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preview so farIm working on an project in which i modeled a stargate and a jumper (spaceship from stargate). I also have some video footage in which i want to place my models. The tracking and camera resolving is done.

Now i have on the one side the problem, that i want some tears/scratches on the ground where the stargate is grounded in (i tried a uv map on the ground (background layer) and created there one with some scratches but in the result there is nothing rendered) - so i tried it with a plane in the foreground cause i thought if the uv map is transparent except of the scratches.. doesnt worked as well. so how i realise this?

the other problem is, that the spaceship should come out of the stargate - so it is animated but should "appear" (like that https://youtu.be/tNSiS9wN-GI ) the problem is, that i dont know if i can use this that easy cause he uses dynamic paint and a node to check greater or lower 1. may you guys have an other idea.

i use cycles renderer, so a lot of solutions i found doesnt work :/

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  • $\begingroup$ You should keep to one question at a time. The ground scratches are a different problem to the emerging puddle jumper. $\endgroup$ – sambler Sep 25 '16 at 5:49
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To animate the puddle jumper coming through the stargate you could use a boolean modifier to hide it behind the event horizon.

sample animation

  1. Create a cylinder big enough to enclose the puddle jumper and place it behind the stargate.
  2. Add a boolean modifier to the puddle jumper and select the previous cylinder as the object and set the operation to difference.

boolean settings

  1. Disable the renderability of the cylinder so that it isn't seen when rendering, or you could give it a transparent texture.

outliner

example scene

Edit:
The easy way doesn't always work. As the boolean modifier doesn't always give a good result with some meshes, it can be better to do it in compositing. By giving the hideout mesh an object index you can use it to create a mask in the compositor. This answer explains using an object ID to composite multiple objects together.

First you want the background to be transparent, by enabling transparent in the film settings (part of the render settings).

film settings

Enable Object Index in the render layers.

render layers

Then give the object an index number.

object properties

Now in the compositor you can add an ID Mask node and connect that to the IndexOB and set the index number to match the number you set for the hideout object. The little box in the mix node will combine the alpha from the render and the mask.

composite example

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  • $\begingroup$ thanks so far. your solution seems quite easy. but i still have some trouble. blend-exchange.giantcowfilms.com/b/2018 in this file i have my jumper and the hideout object. the jumper is hidden at the start but when it starts to apear the whole jumper is apearing. $\endgroup$ – white91wolf Sep 26 '16 at 20:09
  • $\begingroup$ Seems the boolean doesn't like your model, there is a variation to the boolean modifier in 2.78 that is better but it is still glitchy. compositing will be the way to go, thought someone else would have answered with that by now. $\endgroup$ – sambler Sep 27 '16 at 11:08
  • $\begingroup$ wow just wrote an comment, that i downloaded 2.78 and tried it. and it doesnt work. and now i see your edit - thanks a lot!! i try it tomorrow cause today i have no time. but rly thanks $\endgroup$ – white91wolf Sep 27 '16 at 11:59
  • $\begingroup$ used your solution. works great so far - just one (little) issue. i have a bachground layer in which shadow should be casted. and now i get the shadow. i.stack.imgur.com/W5VVk.jpg i tryed to disable the shadow of the hideout object but it still renders the whole shadow of the jumper i.stack.imgur.com/vVZ0A.jpg . one other strange thing is that sometimes i get as result something like that i.stack.imgur.com/NxBkp.jpg - hope you can help me out. if u want i can add the blend file $\endgroup$ – white91wolf Sep 27 '16 at 21:06
  • $\begingroup$ Also use the mask when you mix the shadow - I think the hideout would need to be bigger so that it masks the shadow behind the gate and don't enable the box next to mix type. Probably easier than trying to control the casting of the shadow. $\endgroup$ – sambler Sep 28 '16 at 16:02

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