When used inside a node group in multiple scenes, the defocus node does not refresh active camera data. #38340

New Issue

Sam Brubaker · 2014-01-23T20:20:15+01:00

Sam Brubaker commented

2014-01-23 20:20:15 +01:00

Version: 2.69 official (win 64)

How to reproduce: Render First Scene. The orange cube is in focus, as it is being used as the active camera's focal point. The defocus node is inside a node group used by both scenes. Now, render the second scene. Notice that the orange cube is out of focus even though the active camera is also using it as a focal point.

Expected behavior: Since both scenes are identical except for the cameras, and both cameras use the same focus, the orange cube should be in focus for both scenes. Instead, it seems that the defocus node persists in using the camera distance data from the first scene in which it was originally added.

Defocus_Node_Bug.blend

Version: 2.69 official (win 64) How to reproduce: Render First Scene. The orange cube is in focus, as it is being used as the active camera's focal point. The defocus node is inside a node group used by both scenes. Now, render the second scene. Notice that the orange cube is out of focus even though the active camera is also using it as a focal point. Expected behavior: Since both scenes are identical except for the cameras, and both cameras use the same focus, the orange cube should be in focus for both scenes. Instead, it seems that the defocus node persists in using the camera distance data from the first scene in which it was originally added. [Defocus_Node_Bug.blend](https://archive.blender.org/developer/F74356/Defocus_Node_Bug.blend)

Sam Brubaker commented

2014-01-23 20:20:15 +01:00

Changed status to: 'Open'

Sam Brubaker commented

2014-01-23 20:20:15 +01:00

Added subscriber: @rocketman

Brecht Van Lommel commented

2014-01-23 20:29:15 +01:00

Added subscribers: @Jeroen-Bakker, @monique, @LukasTonne

Brecht Van Lommel commented

2014-01-23 20:34:51 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2014-01-23 20:34:51 +01:00

I think this was added intentionally so that you could do compositing of multiple scenes in one compositing node setup, or use a separate scene for compositing and rendering.

The node remembers the scene, and perhaps that value should be exposed to the user. If empty it uses the current scene, if not you can get the current camera from another scene? I'm not sure what the default should be, perhaps it's least confusing if it's empty and uses the current scene.

I think this was added intentionally so that you could do compositing of multiple scenes in one compositing node setup, or use a separate scene for compositing and rendering. The node remembers the scene, and perhaps that value should be exposed to the user. If empty it uses the current scene, if not you can get the current camera from another scene? I'm not sure what the default should be, perhaps it's least confusing if it's empty and uses the current scene.

Sam Brubaker commented

2014-01-23 20:45:28 +01:00

@brecht, I wondered about that right after I reported this. That "feature" would be useful for just such a thing, but it seems wrong to make it ambiguous to the user.

I agree with your suggestion on how it could be fixed. That way, defocus can be used in one node group across all scenes if I want (I do want).

@brecht, I wondered about that right after I reported this. That "feature" would be useful for just such a thing, but it seems wrong to make it ambiguous to the user. I agree with your suggestion on how it could be fixed. That way, defocus can be used in one node group across all scenes if I want (I do want).

Lukas Tönne commented

2014-01-24 10:11:30 +01:00

This scene-dependency of compositor is quite horrible IMO. It's a quick solution for getting scene info into nodes, but design is weak and it breaks really easy with changing contexts.

Similar issue, where compositing without a scene also doesn't work because of this dependency of the Defocus node: #36745

This scene-dependency of compositor is quite horrible IMO. It's a quick solution for getting scene info into nodes, but design is weak and it breaks really easy with changing contexts. Similar issue, where compositing *without* a scene also doesn't work because of this dependency of the Defocus node: #36745

Lukas Tönne commented

2014-01-24 10:32:46 +01:00

Just for the record, here is a list of nodes which afaict currently store a scene reference in node->id:

Type	Comment
Render Layers	can be selected explicitly by user
Composite	scene is identified by name during composite
Defocus	used only for active camera object
File Output	not used except for initializing output file format

Just for the record, here is a list of nodes which afaict currently store a scene reference in node->id: | Type | Comment | | ----- | ----- | | Render Layers | can be selected explicitly by user | | Composite | scene is identified by name during composite | | Defocus | used only for active camera object | | File Output | not used except for initializing output file format |

Sam Brubaker commented

2014-01-24 16:54:21 +01:00

@LukasTonne , That's a very good observation.

If you want to rectify this scene dependency of the Defocus Node, there could be an additional Input node called "Active Camera Data" which would feed DoF and Focus depth values into the Defocus Node.

That way, the Defocus Node would not need to reference any external scene data by itself. In a perfect system, only input nodes should do that.

@LukasTonne , That's a very good observation. If you want to rectify this scene dependency of the Defocus Node, there could be an additional Input node called "Active Camera Data" which would feed DoF and Focus depth values into the Defocus Node. That way, the Defocus Node would not need to reference any external scene data by itself. In a perfect system, only input nodes should do that.

Brecht Van Lommel commented

2014-01-24 17:30:23 +01:00

I think the standard solution would be to include camera data in the EXR metadata, and in Blender it would also be in the RenderResult then. I couldn't quickly find a standard for this metadata, but if you Google for "exr camera metadata" you'll find a bunch of information about people doing similar things.

Sam Brubaker commented

2014-01-24 23:52:04 +01:00

I agree, @brecht , but which scene's camera data would the output node use? You would still have the same issue as with the Defocus node, in that the node is taking invisible inputs (i.e., camera data) that are not exposed to the user.

If I have an EXR with camera data, but I'm compositing it with another scene with camera data, I would need to specify what camera data goes where. Currently, the Defocus node invisibly pulls the camera data from the scene in which it was first added. How can we unblock the user from choosing the relevant camera inputs for the Defocus and other output nodes?

I agree, @brecht , but which scene's camera data would the output node use? You would still have the same issue as with the Defocus node, in that the node is taking invisible inputs (i.e., camera data) that are not exposed to the user. If I have an EXR with camera data, but I'm compositing it with another scene with camera data, I would need to specify what camera data goes where. Currently, the Defocus node invisibly pulls the camera data from the scene in which it was first added. How can we unblock the user from choosing the relevant camera inputs for the Defocus and other output nodes?

Sergey Sharybin commented

2014-02-04 11:57:26 +01:00

Added subscriber: @Sergey

Sergey Sharybin commented

2014-02-04 11:57:26 +01:00

@brecht, @LukasTonne what would be the plan here?

Lukas Tönne commented

2014-02-04 12:54:00 +01:00

I would suggest to only use scene (or other ID pointers) in node->id when they are real ID block references that can be selected by the user. These would then stay fixed across changing contexts as well, which avoids a lot of ugly code in blenkernel.

For cases where the node->id is actually context dependent (composite, defocus) it should not be used at all. Rather for these nodes the context (which is given for a compositor execution) then defines the actual scene from which to take camera data and output render data.

This should also fix issues where the hard scene pointer gets outdated, see #38473.

It would also allow for flexible behavior as suggested by @brecht above: If no ID is selected by the user, the context can be used instead.

I would suggest to only use scene (or other ID pointers) in `node->id` when they are *real* ID block references that can be selected by the user. These would then stay fixed across changing contexts as well, which avoids a lot of ugly code in blenkernel. For cases where the `node->id` is actually context dependent (composite, defocus) it should not be used at all. Rather for these nodes the context (which is given for a compositor execution) then defines the actual scene from which to take camera data and output render data. This should also fix issues where the hard scene pointer gets outdated, see #38473. It would also allow for flexible behavior as suggested by @brecht above: If no ID is selected by the user, the context can be used instead.

Brecht Van Lommel commented

2014-02-04 13:15:21 +01:00

So I think in practice that means:

Composite and File Output: remove node->id usage and get scene from context
Defocus node: make the node->id scene user editable, and if NULL get scene from the context.

Making camera data something you can read from EXR and pass along in the node editor would be nice but beyond the scope of a bugfix I think, the changes above should be relatively simple?

So I think in practice that means: * Composite and File Output: remove node->id usage and get scene from context * Defocus node: make the node->id scene user editable, and if NULL get scene from the context. Making camera data something you can read from EXR and pass along in the node editor would be nice but beyond the scope of a bugfix I think, the changes above should be relatively simple?

Lukas Tönne self-assigned this 2014-02-04 16:12:16 +01:00

Sam Brubaker commented

2014-02-04 16:22:37 +01:00

That sounds like a fine solution. Thanks, Everyone!