View Full Version : 'Render Buffer Export' Depth problem

06-16-2005, 09:49 AM
I have a problemo.
I want to have an image with Z-Buffer depth so I can blur in Photoshop based on depth, without having to re-render.
Since I don't intend to use Digital Fusion or any other compositing package I can't use RLA or RPF. So, I'm stuck with using 'Render Buffer Export'.

thing is, it's all wrong. At least, the range is.
Look at the image below, I need the Z buffer from that. But the output buffer shows the following image.... quite unusefull. Mind you this is WITH and WITHOUT the 'normalize' tickbox on, it doesnt seem to make a difference.

Anyone a clue as to how to define the range of this depth thing?

06-16-2005, 03:03 PM
bumpix of the excellent question!

06-16-2005, 03:16 PM
This thread:


talks about exporting depth maps to Digital Fusion, seems to indicate that LW doesn't have good depth-map export, and that a tool called "Pel Z Tool" gives good depth-map options.

I've never used it, but it sounds like you're getting desperate! Good luck!


06-16-2005, 08:54 PM
If you set up your scene with black objects and white fog you can make a depth map however you want it.

Do you know a way of masking the actual blur size with the map? Meaning for example 0 pix blur at 100% black fading to 10 pix blur at white. I've tried masking a straight blurred image to a sharp one with the z-pass, but it's not the same.

06-17-2005, 02:06 AM
It's also worth bearing in mind two things - the first is that this depth map will have been calculated at LightWave's floating point depth, which when converted to an 8-bit per channel image will lose definition, and also that it's good to set limits for the depth buffer, otherwise it will attempt to calculate to an infinite distance making the graduations impossibly fine. Try putting an object just outside those windows in order to give LightWave something more to calculate from.


06-17-2005, 02:57 AM
Monroepoteet: I can;t find this Pen Z tool, and I was hoping this could be done outside of DF... :\

Toby: That is actually a pretty neat idea. However, it is a shame it needs 2 separate renders this way. I'll certainly try it and see if I can come up with something.

Beevee: Ok, I'll put a box or something outside of the windows and see if it helps. But If I understand correctly, if I render the Z buffer to a .hdr, I could, in theory, get a good image out of it using HDR shop, or load it back in and poke around with the Exposer plugin?

06-17-2005, 04:44 PM
I wrote a quick plug-ins to export the internal depth buffer as a grayscale image. The difference from Render Buffer Export is you can specify the minimum/maximum values for the range, or have the plug-in calculate it from the next frame rendered.

It's an Image Filter plug-in, so add it using CTRL-F8. It has a panel for specifying the options, which I think are pretty straightforward. Hope it helps.


06-18-2005, 04:16 AM
Holy moley!
Thanks so much!

Its an excellent plugin!
Just render once with 'Recalculate Min/Max' on, on a very low quality setting, then boost all the settings again and render, and voila!

(this is, by the way, of an adjusted scene)

Hey, do you have a website where this is hosted? Because I think a lot of people would be very happy with this. I can host it on my servers if you like?

06-18-2005, 12:05 PM
Glad it works for you. It's kind of hosted here, IMO, and it seems like this would be a logical place for people to look if they're having similar problems. Thanks for the offer, though.