[Cloudman]

Hi

How do I access the object ID channel in Photoshop? I can see it when I open the single tif file in Apple Preview but can't locate the channel in Photoshop.

To be honest, I'm a little confused how Maxwell handles this, as sometimes it will output a separate object file and other times it embeds it in the tif.....how do I control this output? I render files out with the render and object ID toggled on.

Here's a screenshot from Apple Preview showing all the channels in the single .tif:

[Mihai]

Whether they are embedded or separate files can be chosen from Output mode in the render options:

http://support.nextlimit.com/display/ma ... s/Channels

You should be able to see the channels from the Channels palette in PS.

[Cloudman]

You should be able to see the channels from the Channels palette in PS.

That's what I thought, however when I look at the same file in PS (CS4) I only see the RGB channels......

[Mihai]

Could you send me the TIF file?

[Mihai]

Just found out that PS can't read multi page tiffs properly....it's the same issue with EXR files in which case you would need this plugin: http://fnordware.com/ProEXR/ to be able to read/write layers in exr format.

Just wondering though, why not open the MXI directly in PS and work from it?

[kami]

Hi Mihai
I got a question concerning openig the mxi in photoshop. When you import it, you get a layer for ObjectID and for MaterialID. For selecting the materials, it is quite fast with the magic wand, but also kind of inexact. If I make strong changes in lighting or color of the material, I always get 'glowing edges'. I usually can get rid of them with refining the edge of the mask, but this takes some fine tuning and a lot of time.
Now, when working with a strong DOF, these colorful selection images are blurred as well and it is not really possible to use these masks at all, or am I overlooking something?
Thanks, kami

[Cloudman]

Thanks for looking into this. It's not so much a problem now that I realise I can export them as separate files for compositing.

I wasn't aware you could read mxi files into PS.....I'll try it.

[brodie_geers]

Maybe some other folks can chime in with tips regarding object and mat id selection, but here are mine.

Use Select -> Color range and the selection will be much better. I usually try to adjust the slider so it selects as much of the color as possible. If it happens to select some other similar colors as well I'll go ahead and just deselect them after finishing up with the Color Range tool. I also recommend using adjustment layers so you have a mask. Not only can you go back and adjust the mask if something changes but it's nice to go into the mask view to make sure the selection looks correct.

This would be quite difficult with Maxwell and I've never done it although I like the concept and it could work well if you have just a few things you know will be changing. The idea is to change all of your ID's to black except for 3 which you change to pure red, green, and blue respectively. Then in photoshop you can go to the Channels tab and use the Red, Green, and Blue channels to make your selections.

-Brodie

[eric nixon]

The industry standard way to make object id / material id channels is to ONLY USE PURE R,G.B. This means in PS you can use the RGB channels of the layer to create perfectly antialiased mattes. Unfortunately this means you can only assign 3 id's for rendering so you may need to render more than one object id / material id pass. All other objects are given a pure black id colour.

Sorry just realised I'm repeating what Brodie said in his last paragraph.

[Mihai]

I wasn't aware you could read mxi files into PS.....I'll try it.

The MXI plugin has been around for about a year and a half. Download it from the customer portal.

http://support.nextlimit.com/display/ma ... /Photoshop

The industry standard way to make object id / material id channels is to ONLY USE PURE R,G.B.

What happens in case the saved image is in 32 bits? Wouldn't you have much more possibilities to select something, more than 256 levels of a color.

[brodie_geers]

What happens in case the saved image is in 32 bits? Wouldn't you have much more possibilities to select something, more than 256 levels of a color.

I'm not a PS pro but it seems 32 bit is actually worse. In PS you can't use the Color Range or Wand tools in 32 bit mode for whatever reason making selecting anything nigh impossible. Besides, you've actually got 16 million choices (256x256x256) already as I understand it. The problem is that if you select just the specific color of the ID then PS won't select any of the AA parts. If you widen the range to accept all the AA parts, you're libel to find that some of the other ID colors in the image fall within that range as well.

-Brodie

[Cloudman]

I wasn't aware you could read mxi files into PS.....I'll try it.

The MXI plugin has been around for about a year and a half. Download it from the customer portal.

That'll teach me to not keep up with the plugins. Just tried it......exactly what I needed

[feynman]

That's interesting, often have same problem and spend hours on mask painting. What is in your opinion best practice in order to select an object/material id when faced with depth of field images - are you saying that the "all black + rgb" method is the only easy way for very fuzzy edges of one object against another? That's not so nice. Would be a good option, if one could render separate channels for objects/materials also.

The industry standard way to make object id / material id channels is to ONLY USE PURE R,G.B. This means in PS you can use the RGB channels of the layer to create perfectly antialiased mattes. Unfortunately this means you can only assign 3 id's for rendering so you may need to render more than one object id / material id pass. All other objects are given a pure black id colour.

Sorry just realised I'm repeating what Brodie said in his last paragraph.

[Gary Bidwell]

I'd be interested in this too.

The red, green and blue colours works well - cmd clicking the r g or b channel gives a good selection, but I'd be interested in how to cleanly pick up a non rgb colours.

Cheers,

Steve

[lifeofdave]

I've found the only reliable way is to render mattes in another program. Either rgb mattes from lightwave or black and white alphas from modo. In Modo you can set it to render an alpha for any object or material, would love to see something like this in Maxwell one day.