Alpha Hiccup

[Simon Edmondson]

Using V15J on an Imac with OSX 10.68

 

I am having trouble with the alpha channel on renders.

 

 

This is a Jpg conversion of the TGA file rendered with the Alpha on

 

 

 

This is the same frame ( again converted to jpg ) rendered with the alpha off.

 

I rendered some exr sequences at the weekend with light buffers turned on but they are now turned off and the setting are 'normal'

 

I have rendered out sequences with alpha included before and not had this problem, can anyone kindly suggest what the problem might be and how to correct it ?

 

regards

simon

[Rodney]

There are a few things we don't know here but I assume you are doing your conversion in A:M?

 

Since JPG doesn't have an Alpha Channel I'm not sure what you are referring to there.

A:M shouldn't even allow you to turn Alpha on for JPG images.

 

Perhaps I'm not fully understanding the problem.

 

If what we are seeing through the window doesn't have any background then I'll wager that there is nothing there n the background and therefore in the TGA image that area is rendering correctly by showing black as areas that are transparent (i.e. those areas effected by the Alpha channel). Since JPG doesn't have an alpha channel it is doing it's best to show through this Alpha Channel and likely to your camera background color (perhaps still the default blue color?) in showing through in the JPG.

 

It sounds to me like you haven't converted the file as much as rerendered it and the Alpha is being maintained.

 

If what I've stated above is indeed the case then there are at least two ways to proceed:

 

1) Renderer the scene with the Alpha off (this should yield a similar image as the JPG though so you'll probably want to have something in the background (or change the default camera background color)

 

2) Render straight to JPG which will not give you an Alpha (since there is nothing in the background you'll want to either put something there... or change the camera's background color)

 

My gut feel may be wrong but it seems to me that you are getting what you are asking for but aren't realizing the effect of the transparency created by using the Alpha with nothing in the background.

 

Using V15J

 

I can't recall if there were any know issues with Alpha's in v15 but that is also a possibility.

 

You said this before:

This is the same frame ( again converted to jpg ) rendered with the alpha off.

 

Can we assume this is the look you are after?

If it is then you should render with the Alpha Channel off.

[Rodney]

It occurs to me that you might be wanting to composite this shot over the top of another.

If this is the case then you won't want to use JPG because you'll have lost your transparency/Alpha.

 

One way to see the full effects of the Alpha with the TGA is to bring that into a program that correctly reads Alpha channels and mess with whatever is in the background. In A:M you could drag and drop the image into A:M and when asked what to bring the image in as select "Layer". (You could chose Rotoscope too but if you haven't used Layers you should experiment with those too).

 

With the TGA image in the Chor then change the camera's background color to red or some other color that will be easy to spot. You should see that color through the transparent parts of the TGA image. Rendering out to JPG will result in a similar image.

 

If you have a program like Photoshop or Illustrator it'll be easy to see the effects of the Alpha in real time as well by placing any object/layer behind this TGA image. When saved back out the results should be similar and include (parts of) whatever was in the background (i.e. whatever masked for transparency via the Alpha Channel)

[Simon Edmondson]

I can't recall if there were any know issues with Alpha's in v15 but that is also a possibility.

 

Rodney

 

That was very quick, I'd only just eaten lunch...

Thank you for your reply.

 

The files were rendered in AM to a TGA format. One with the Alpha on, one with it off.

Those files were then 'saved as' with preview under OSX ( the reason for that was because of previous mistakes on my part were I uploaded TGA files).

 

It may be my misunderstanding, as there is nothing the other side of the window except the rim light acting as the lightening. When the render is going through the information I expected to be there, was, as each of three passes completed. Then, when the final part of the render completed, the previous info seemed to vanish and I got the transparency of the alpha channel with no reflections of the room.

 

When the chor was rendered as a QT file this was the result

S1_000.mov

 

And it was that room reflection that I was expecting with the still files but didn't get?

Thank you for your help

regards

simon

[Simon Edmondson]

It occurs to me that you might be wanting to composite this shot over the top of another.

If this is the case then you won't want to use JPG because you'll have lost your transparency/Alpha.

 

One way to see the full effects of the Alpha with the TGA is to bring that into a program that correctly reads Alpha channels and mess with whatever is in the background. In A:M you could drag and drop the image into A:M and when asked what to bring the image in as select "Layer". (You could chose Rotoscope too but if you haven't used Layers you should experiment with those too).

 

With the TGA image in the Chor then change the camera's background color to red or some other color that will be easy to spot. You should see that color through the transparent parts of the TGA image. Rendering out to JPG will result in a similar image.

 

If you have a program like Photoshop or Illustrator it'll be easy to see the effects of the Alpha in real time as well by placing any object/layer behind this TGA image. When saved back out the results should be similar and include (parts of) whatever was in the background (i.e. whatever masked for transparency via the Alpha Channel)

 

Rodney

Pardon me, I was typing the reply while you were typing this one.

I was going to try some compositing with the EXR's mentioned, using the light buffers, I was getting a bit exasperated with the png's rendered and, after last weeks intro to compositing, thought I'd try that. I will try the method above later.

I must confess I'm getting into a bit dizzy with it all at the moment.

regards

simon

[robcat2075]

Post one of the TGAs that you regard as bad.

[Simon Edmondson]

Post one of the TGAs that you regard as bad.

 

 

Robert

Heres the unconverted TGA.

Thank you and Rodney for your help.

regards

simon

 

Stormy_C1__073.tga

[robcat2075]

I guess I'm not sure what you rendered to get this or what the desired result is.

 

What do you want to do with this image that needs an alpha channel?

 

The alpha channel i see in this image has two white bands at the side and a large dark grey (51,51,51) area in the middle.

[Rodney]

Here is what is stored as a mask for the Alpha Channel:

 

Black=Transparent

White=Opaque

Gray=Somewhere in between based on the gradation

 

This Alpha Channel mask is what tells a program/browser/utility to what extent to display the Red, Blue and Green (RGB) channels.

Black and it won't show anything

White and it'll show everything

Gray and it'll show a partial transparency of what is stored in the RBG.

 

This seems to validate what I was saying before with regard to your background color bleeding through and altering the color of the entire image.

 

Layers... drag and drop a bunch of images with Alpha Channels into the Chor as Layers (preferrable to rotoscopes for the purpose of compositing experimentation). Move them around. Rerender everything and bring it back into A:M again. In no time at all you'll have a great grasp on how to leverage Alpha Channels in A:M.

[Rodney]

For completeness sake I'll post the final along with the Red, Green and Blue channels:

 

The RGB channels operate the same way as the Alpha Channel in how they mask their respective colors.

Black... less of that color. White... all of that color. Gray... midtones

 

 

Whenever using an image with an Alpha Channel there is one additional consideration that must be made and that is where the image itself will be placed. If it is place on a white background the transparent areas will make the image look brighter in the midtone/unmasked areas and the reverse will be true if the background is black... it'll darken any midtone/transparent areas. Of course as has been previously noted, a full black masked area will let all the RGB through (so it'll appear transparent) and a full white masked area won't let any through so all of the RGB will be seen.

 

What complicates this matter is that many programs don't allow the viewer to easily distinguish between the mask of the Alpha Channel (which is black remember) and the black areas of the image, so that black alpha channel on a black image will just look black to them. The test for this would be to render something that is completely black with an alpha channel. Then change that object to white. Compare the two images and you'll see that the Alpha Channel mask is the same but the RBG channels are not.

[Simon Edmondson]

Rodney and Robert

 

Thank you once again for your help

I think the problem starts with confusion on my part. I was expecting it to look like it did going through ( as previous experience suggested ). I misunderstood what was going on,

I'll get there slowly.

regards

simon

 

Ps

I'll try layers this evening. In my own defence I was a bit confused when I tried to open the TGA and some PNG files in Photoshop and couldn't access the alpha channel but again, I think thats inexperience!

[Rodney]

I'll try layers this evening. In my own defence I was a bit confused when I tried to open the TGA and some PNG files in Photoshop and couldn't access the alpha channel but again, I think thats inexperience!

 

When it comes to leveraging Alpha Channels join the club. We could all be using Alpha Channels far more than what we do now.

 

I'm more at home with Corel Photopaint than Photoshop but in most 2D paint programs Alpha Channels will come in either as masks (usually painted red) or as those crawling squiggly lines that everyone loves to hate with the background a checkerboard pattern. Each program has a different way of displaying transparency. Of course these methods of display can be changed.

 

In A:M the previews just display the Alpha Channel as black but when in use the full realtime transparency is displayed.

 

Something that is useful to know is that in A:M's Composite there is a Post Effect called Channels.

There you can specify a Red, Green, Blue or Alpha channel to use in a Composite, as a Rotoscope or elsewhere where Composites are allowed. To alter the settings we don't change the settings in that location but back under the Composite itself.

 

Now you've got me wanting to test some things in Composite...

[Simon Edmondson]

Preparing to follow Rodney's suggestion for using channels in composite, I thought I would follow Xtraz's idea and use an obj tree to put in the background, to be viewed through the alpha channel in an earlier shot.

 

I dl'd a free tree in 3Ds format and used the import plug in. Or rather, I am trying to.

Its been going at it for about 6 hours now and still only 60% through. Is this normal. I tried some OBJ files on another machine and they imported within seconds.

Just when I thought the learning curve might be easing!

regards

simon

[Rodney]

Just when I thought the learning curve might be easing!

 

If you are importing .OBJ files to populate your scene your learning curve has just gotten a whole lot more steep.

 

Is this normal.

 

No, it is not normal to torture yourself needlessly.

 

If you can build the asset in A:M... just a recommendation... build it in A:M.

Then you'll see your learning curve ease considerably.

 

I suppose if you really want to import an OBJ or 3DS you could built the model in A:M and export it out to one of those formats.

Then import it...

 

Have you used the Treez plugin before?

Using that for the trunk and Hair images for the leaves might be a better approach to creating trees in A:M.

[robcat2075]

I don't think you've really explained what you are trying to do. Without that, it's hard to solve your problem. I've done a lot of compositing. It isn't hard. But i don't know what you are trying to do.

 

I believe some fundamental misunderstanding is at work here.

[Simon Edmondson]

I don't think you've really explained what you are trying to do. Without that, it's hard to solve your problem. I've done a lot of compositing. It isn't hard. But i don't know what you are trying to do.

 

I believe some fundamental misunderstanding is at work here.

 

Robert

 

My mistake.Sorry

Having encountered the difficulties with the alpha channel mention before, I thought I would try to learn it properly and address a suggestion from earlier in the WIP thread, by compositing an exterior into the first scene ( the only one, other than the credits ) with the curtains open.

 

Using a tree seemed like a good idea so I thought I would use a ready made model. Set that up, render it, then composite it within AM.

 

Rather than start a new thread, I asked here about using the plug in converter for 3Ds files, as that was one of the free models I had found. The conversion had seemed a bit long at 6 hours has now been churning away for nearly 18 hours and still only at 60%. It serves me right for trying to short cut I suppose.

 

I will try the treez plug in.

 

Regards

simon

[markw]

Hi Simon

Be very careful with the treeez plugin!

The first time I used it I wanted to make just one tree and then found I had spent a whole Sunday afternoon tweaking things and making more and more.

It can be addictive!

[Simon Edmondson]

Hi Simon

Be very careful with the treeez plugin!

The first time I used it I wanted to make just one tree and then found I had spent a whole Sunday afternoon tweaking things and making more and more.

It can be addictive!

 

 

Mark

Thank you for the caution. Ideas started forming for future use but, I'm just trying to finish off what I'm working on. It was only going to take a week ( hollow laugh ) but I have learnt a LOT in the process.

regards

simon

[Rodney]

Rather than start a new thread, I asked here about using the plug in converter for 3Ds files, as that was one of the free models I had found. The conversion had seemed a bit long at 6 hours has now been churning away for nearly 18 hours and still only at 60%. It serves me right for trying to short cut I suppose.

 

It's not wrong to experiment... that's always a good thing. But when adding in an unknown file or process into the mix such and having A:M convert a model from polygons to patches that skew the results of the original experiment considerably. Some people might even equate the use of alpha channels with the time that it takes to convert models... which would be most unfortunate because the use of alpha channels can be demonstrated almost instantly.

 

See this as an opportunity to simplify your approach to experimentation in that we can all learn from how the best in the business approach their research; they tend to simplify and isolate things. As a for instance, to test a material, a model, an alpha channel... practically anything... it can help to work with exceedingly... almost humorously to the point of being ridiculous... simplicity. Then as success in that basic workflow is achieved complexity can be added to meet more specific needs. There may be times where a 16 hour conversion of OBJ/3DS files is worth the time invested. However, in a majority of test cases just a simple patch may be all that is needed.

 

A great way to test things like alpha channels is to simply extrude a patch, create a grid or lathe an easy shape and then experiment with that. The benefit is that you won't spend time in the setup and you can get right to your point of interest. Success leads to more success through simplicity.

 

This is not to say that all experimentation isn't valuable in some way. Right now you are learning something about the process of converting 3DS models and the amount of time that can take. If ever needed you'll know more about the time that it can take. And others seeing this process, if they are paying attention, will know what to avoid in their own experimentation.

 

When it comes to things like trees... that is something that I hope we can help with in the forum by adding such basic resources to the A:M Exchange Model's section. If a good variety of trees was there then you wouldn't have to spend a whole lot of time creating/importing/converting them. You could just tweak to taste.

[robcat2075]

My mistake.Sorry

Having encountered the difficulties with the alpha channel mention before, I thought I would try to learn it properly and address a suggestion from earlier in the WIP thread, by compositing an exterior into the first scene ( the only one, other than the credits ) with the curtains open.

 

So what you are wanting to do is render your 3D room with an open window and composite a 2D image of trees behind that, so they can be seen through the window? Does that describe what you are trying to do?

[Simon Edmondson]

So what you are wanting to do is render your 3D room with an open window and composite a 2D image of trees behind that, so they can be seen through the window? Does that describe what you are trying to do?

 

Robert

Exactly so.

I'm working through the tutorial for Treez now and hope to be able to post something later today as a result. I'll post it in this thread because its relevant to the compositing theme.

 

regards

simon

 

Ps

If I had known how easy it was to use Treez I would not have bothered with the import option.

Pardon my error.

[Rodney]

I'm working through the tutorial for Treez now and hope to be able to post something later today as a result. I'll post it in this thread because its relevant to the compositing theme.

 

 

If I had known how easy it was to use Treez I would not have bothered with the import option.

Pardon my error.

 

Not to distract you further but since you are experimenting with trees...

 

One way to create trees would be just to draw them with splines and then use Sweeper to 'loft' patches that taper out to the end of the branches. A similar approach could be done to create the leaves but instead of extrusion Sweeper would be set to copy a leaf onto all of the splines where they need to be.

 

I'll see if I can't wip up a video tutorial that demos the basic principle... I've never done it myself but know that it's possible so it'd be a good experiment for me.

[Simon Edmondson]

Not to distract you further but since you are experimenting with trees...

 

One way to create trees would be just to draw them with splines and then use Sweeper to 'loft' patches that taper out to the end of the branches. A similar approach could be done to create the leaves but instead of extrusion Sweeper would be set to copy a leaf onto all of the splines where they need to be.

 

I'll see if I can't wip up a video tutorial that demos the basic principle... I've never done it myself but know that it's possible so it'd be a good experiment for me.

 

Rodney

Thank you for the kind offer. I would be very interested in the tutorial for the next project I will try to get this done for now.

From what I've read in the archives I would guess that such a tutorial would be welcomed by many, as well as me.

regards

simon

[robcat2075]

So what you are wanting to do is render your 3D room with an open window and composite a 2D image of trees behind that, so they can be seen through the window? Does that describe what you are trying to do?

 

Robert

Exactly so.

 

 

In that case you can do this without resorting to compositing or alpha channels. Put the 2D image of a tree on a flat patch, make the flat patch 100% ambient, and put it outside the window.

[Simon Edmondson]

In that case you can do this without resorting to compositing or alpha channels. Put the 2D image of a tree on a flat patch, make the flat patch 100% ambient, and put it outside the window.

 

 

BLAST !!!

I've just spent the afternoon learning how to make trees and the render is going through for the compositing...

 

I need to learn how to do it though so not wasted time.

 

Its an idea I'll use next time though. I'm curious the "100% ambient" setting you suggest. What affect and result would that chaznge ?

regards

simon

[robcat2075]

It's easier to find the right answer when the problem is clearly stated.

 

Its an idea I'll use next time though. I'm curious the "100% ambient" setting you suggest. What affect and result would that chaznge ?

regards

 

When you put any decal on a model surface the appearance of te decal will be darkened by the normal shading of the model and lights. Set the model to 100% ambient and all shading disappears.

[Simon Edmondson]

There are some glitches in this that haven't appeared before, which I will try to iron out today but, Here a low res of the first composite.

Simon

 

Landscape_000.mov

[Rodney]

It's looking good from here.

 

My first thought was that he might be reacting a bit too early to the lightning but it's close enough to work.

It seems clear to me that he is reacting to the lightning.

 

 

 

It's looking good from here.

 

My first thought was that he might be reacting a bit too early to the lightning but it's close enough to work.

It seems clear to me that he is reacting to the lightning.

 

Added: I should say that I don't really know what has been composited in this scene and so I'm not sure what specific feedback you are looking for.

[Simon Edmondson]

Added: I should say that I don't really know what has been composited in this scene and so I'm not sure what specific feedback you are looking for.

 

Rodney

Thank you for your feedback

 

The outside view is the background and the interior with figure has been composited on top of that.

 

I'm not happy with the level of the reflections in the window. You mentioned that it is possible to adjust the channels in composite. Could you direct me to some instructions on how to do that ?

regards

simon

[robcat2075]

That is so dark I can't see much except when the flashes happen

 

I'm not happy with the level of the reflections in the window. You mentioned that it is possible to adjust the channels in composite.

 

One scenario would be to do a render with the window as a 100% reflective mirror, and another render with the window missing entirely.

 

Use the alpha channel from the second render as a mask in a compositor to vary the transparency of the window area and reveal another layer with the exterior behind it.

[Simon Edmondson]

That is so dark I can't see much except when the flashes happen

 

One scenario would be to do a render with the window as a 100% reflective mirror, and another render with the window missing entirely.

 

Use the alpha channel from the second render as a mask in a compositor to vary the transparency of the window area and reveal another layer with the exterior behind it.

 

 

Robert

Thank you for your reply and suggestions.

 

This was what I was expecting from the reflections. It is exactly the same scene, with same settings, except that it is rendered as a QT movie rather than a sequence of TGA frames with an Alpha buffer. No compositing.

 

One_QT.mov

 

 

I had some trouble a few weeks back, which you kindly helped me with, were the renders were too dark, I am still experiencing trouble with that. It is rather frustrating.

 

Before I go any further, I need to check that I'm doing what I think I am ( !!! )

 

The exterior landscape in the Scene One 000 file was rendered as a 320 x240 TGA sequence ( no alpha), then imported into the PWS and put on a layer.

That was put as the bottom layer in the chor.

The interior scene was rendered as a 320 x 240 sequence ( with alpha), imported into the PWS and put on a layer.

That was then put on top of the other layer in the chor.

 

That was then rendered out as the Scene One 000.mov file, in my post above.

 

The process outlined here is what I understand as compositing. I hope that is correct ?

 

regards

simon

[robcat2075]

The simplest workflow to adjust the effect of the window is to adjust the reflectivity and render a test frame and repeat that until you like the result. But I presume you have done that so there must be something else you don't like.

 

More specifics are needed.

[Simon Edmondson]

The simplest workflow to adjust the effect of the window is to adjust the reflectivity and render a test frame and repeat that until you like the result. But I presume you have done that so there must be something else you don't like.

 

More specifics are needed.

 

Robert

 

I have done multiple test renders and adjustments, not just once but several times. When the problem came to light a few weeks ago. I followed Nancy's suggestions and got it to where I liked it with the reflection there but not too strong.

 

On a number of occasions I have gone back to the same scene and, without having moved or adjusted anything within the chor or models in the interim, the output has changed. The problems with the alpha channel that started this thread was a case in point.

 

In the WIP thread on the project, I had rendered out to TGA with an alpha, and then tried to find a suitable background to put in. With mixed results but the alpha worked as expected. When I came to render that scene again the results were different.

 

The two mov posted today illustrate that problem. In the one rendered as a TGA sequence, ( then converted to Mov ) the results come out dark and the reflection is not visible most of the time.

In the one rendered straight to mov the results were as desired. The settings in the chor, and render window had not changed, except for the output format.

 

I'm trying to get the project finished so, I'm rendering out to a Mov at HD1080 overnight. If that works I'll do the next 5 seconds after that, tomorrow night, the same Sunday and hope to have it done for Monday.

 

I'll crack the compositing eventually but, in the meantime, I have redone the scene by adding the exterior to the chor as models and that is what is rendering out as I type.

Its been a 'character building ' day.

regards

simon

[Rodney]

Now would be a bad time to say I like the dark one?

 

I do like the dark one. It just works for me.

[Simon Edmondson]

Now would be a bad time to say I like the dark one?

 

I do like the dark one. It just works for me.

 

 

I'll post the first section tomorrow, ( I'll have to compress it first I suspect ) the window is much better but, like you, I prefer the darker interior.

Too many B & W noir movies I guess !

regards

simon

[Simon Edmondson]

I'm working on a composite using this as the background image, the window looks much better in this but, like Rodney, I prefer the darker interior.

 

When I import it into the PWS as an mov file, then make a layer using that file for the background, it doesn't show up in the chor. Is there a button I have missed ? The single file sequences show up but not the mov file.

 

I was just looking at it again while waiting for the upload, and noticed it was imported at 600 fps ( !). I've corrected it to 25fps but it still doesn't appear on the layer in the chor ?

regards

simon

 

Scene_HD_A.mov

 

V15J OSX 10.68

Imac 3.3.

[Rodney]

When I import it into the PWS as an mov file, then make a layer using that file for the background, it doesn't show up in the chor. Is there a button I have missed ? The single file sequences show up but not the mov file.

 

I was just looking at it again while waiting for the upload, and noticed it was imported at 600 fps ( !). I've corrected it to 25fps but it still doesn't appear on the layer in the chor ?

 

Are you sure you are using a Layer and not a Rotoscope?

 

While it may seem trivial, the terminology is important.

Layers will show up better than rotoscopes in that they don't have to be specifically told to show up in a render. The assumption being that you will want to see any Layers you add into your scene in the render.

 

This is not the case with Rotos in that Rotos are often used as a means to assist a production and the filmmaker does not always want that Roto to be visible in the final rendering. As such there are settings that tell A:M whether or not to include the images in the render. Rotos also will only appear from specific perspectives (usually cardinal directons of left, right, top, bottom, front and back) As such they cannot be roto-tated (We need to use Layers to rotate images). The exception to this is a Rotoscope that is applied to a Camera. The Camera's POV allows a Roto to be seen from the front of that perspective. There are also those settings under a Roto that specify whether or not to include the Roto in the Alpha Channel. If not selected... the Roto will be left out. Also note that there is the 'On Top' setting which is very handy for placing overlays on top of your screen. That allows those elements/images to never have anything render over them.

 

So by knowing how rotoscopes work this helps us in understanding what might have gone wrong in your specific case.

Perhaps you've added your Roto to your Choreography but NOT to the camera?

If you just dragged and dropped the Roto into the Chor then you'll have to change your view to a cardinal direction (try Front view) to see the image.

 

But back to the original question, are you sure you are using Layers or are you using a Rotoscope?

 

If using Layers I'll guess that the layer is behind something that is masking it... for instance, perhaps it is hiding underneath the Ground.

[Simon Edmondson]

Are you sure you are using a Layer and not a Rotoscope?...

 

If using Layers I'll guess that the layer is behind something that is masking it... for instance, perhaps it is hiding underneath the Ground.

 

Rodney

 

Thank you for your reply.

 

I'm sure I'm using layers.

I followed your instructions. on Objects, selected Layer, selected the Mov file from images.

Repeated that for the image sequence.

Dropped the first layer on the camera, positioned the field of view carefully, dropped the second layer on the camera, positioned it carefully with the cross hairs.

The image on the second layer showed in the camera view but the first one didn't.

I'm fairly sure the ground is not in the way but can't check until the second section of frames has finished rendering ( tomorrow ).

I'll check and try again then.

regards

simon

[Rodney]

Dropped the first layer on the camera, positioned the field of view carefully, dropped the second layer on the camera, positioned it carefully with the cross hairs.

 

Layers cannot be dropped onto Cameras so... you've lost me here.

[robcat2075]

Tell me if my understanding of what you are trying to do is completely wrong...

 

SimonsRoomSetup.mov

[Simon Edmondson]

Tell me if my understanding of what you are trying to do is completely wrong...

 

SimonsRoomSetup.mov

 

 

Robert

 

Thank you very much for the mov file. I was going to follow up your earlier suggestion of that technique after I had got this finished. It isn't what I was trying to do now but it is something I want to try. We talked a few months back about a trailer for Turner Classic movies that used that technique to make a clip look like an Edward Hopper painting of a woman on a train and I wanted to try that soon. If I understand what you are suggesting correctly, the background flat would stay, as is, and be unaffected by the lighting changes ?

 

Its possibly the wrong way to do it but, what I wanted was an exterior that would react to the lightening at the same time as the interior. I built an exterior using the Treez plug in, positioned it in the camera view, deactivated the room model and figure, then rendered the landscape with the same lighting, as a series of TGA files. These were the ones I put on a layer and then composited the interior over the top off.

 

When that didn't give me the result I wanted, I reactivated the room and figure and rendered it with the models outside of the window. That is the one going through now.

 

I've just realised, while typing, that I could use your suggestion and map the rendered exterior onto the flat as a sequence, and have that play through as the whole chor was re rendered. (?) H'mmmmmm.

 

I must admit that it has been a bit frustrating at times the past few days so, I will try your suggested technique next week and just let the current render go through so I can get it to my friend to do the sound for me.

 

Thank you for your help.

regards

simon

[robcat2075]

. If I understand what you are suggesting correctly, the background flat would stay, as is, and be unaffected by the lighting changes ?

 

You don't have to do the Ambience thing. Leave that out and it WILL be affected by lights. But your background, whether it is models or a flat image will almost certainly need to be lit with different lights than your room interior. You can use light lists to keep the lights segregate the effects of lights.

[Simon Edmondson]

You don't have to do the Ambience thing. Leave that out and it WILL be affected by lights. But your background, whether it is models or a flat image will almost certainly need to be lit with different lights than your room interior. You can use light lists to keep the lights segregate the effects of lights.

 

 

Robert

 

Thank you once again.

How do you access light lists and are there any specific instructions available for that option?

regards

Simon

[Simon Edmondson]

Dropped the first layer on the camera, positioned the field of view carefully, dropped the second layer on the camera, positioned it carefully with the cross hairs.

 

Layers cannot be dropped onto Cameras so... you've lost me here.

 

Rodney

Apologies.

I had the camera view active when I dropped the layer into the chor.

I dropped it into the window rather than on the PWS icon. Could that be the problem ?

I did check its position in the left and top views as well to make sure the field of view fitted.

I'll try it on the PWS icon tomorrow..

regards

simon

[robcat2075]

How do you access light lists and are there any specific instructions available for that option?

 

Try this

 

http://www.hash.com/forums/index.php?showt...p;hl=light+list

[Simon Edmondson]

While trying to decide what to do with the project as a whole, I spent this afternoon trying to find out if I understood a little of what I have been told here.

Here is a brief test. Its supposed to look a bit like the interior of a train going through a desert.

The interior was blocked through and rendered to TGA, The backdrop is a single frame, moved in the composite, using the multi plane option.

 

Now back to work.

simon

 

Carriage.mov

 

Ps

Robert

Thank you for the light list tutorial. Much appreciated.

[robcat2075]

Looks like that works!

 

(the sun is in front of the cacti, however. There's probably an alpha channel solution for that too.)

[Rodney]

Very nice example of compositing.

[Simon Edmondson]

Looks like that works!

 

(the sun is in front of the cacti, however. There's probably an alpha channel solution for that too.)

 

 

I was trying to be too complicated earlier and had three layers for the foreground, middle and distance, intending to move them at different speeds.

The sun had to stay static because of the relative movements.

I messed up the alpha channels, so rendered a backplate and made the sun part of the interior setup.

Thats why it goes in front of the cacti. Next time I'll get it right !

regards

simon