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View Full Version : Quote: "lobbying for a decade for LW to add vertex normals".



wizlon
09-05-2006, 10:57 AM
My question is, after reading what I posted below, has Lightwave 9 added vertex normal data?

Here is a reply from Robert Lansdale CEO of Okino Computer Graphics makers of Polytrans CAD conversion software, when asking about Converting CAD files (solidedge) to Lightwave.

"Hello Lee,

>Hi, we are currently having problems with our conversion process and are
>looking for help and advice on how to achieve the best results.
>
>Note: Once the files are in modeler setting a low smoothing angle (between 5
>and 20) with give you a smoother looking object.

Yes, this hasn't changed since I did my first CAD conversion in 1994. I use 23
degrees as my favourite smoothing angle. Since there is just one smoothing
angle per material per mesh, you simply need to make sure there is no cases
where a mesh has both sharp and smooth angles (such as a rotor of a CAD
assembly).

Below is the info I've had in my CAD FAQ for the last 11 years. There really
isn't much that can be done since this has always been an inherent major
problem with LW. I've been lobbying for a decade for LW to add vertex normals.
-------------------

Q: What advice do you have for importing CAD models into Lightwave?
A: Lightwave needs special attention and instructions in order to properly
import CAD models. Lightwave and 3ds Max have their origins in the mid-1980’s
and both still cling to the usage of approximating “smoothing groups” instead
of accurate vertex normals, the latter which is the modern method of
representing mesh smoothing. Smoothing groups have the most problems with CAD
data where they are a lot of abrupt angular changes within a single mesh
object. To compound the problem Lightwave only allows a single smoothing angle
to be defined per mesh object which can be very limiting. Due to these facts,
you will have to “guess” an appropriate smoothing angle for your data when
exporting to Lightwave files via the “Geometry Smoothing Angle” type-in box on
the Okino Lightwave exporter. In general, use a smoothing angle between 18 and
30 degrees. After import into Lightwave you can interactively set this
smoothing angle with the material editor.

Regards,

Robert Lansdale, Okino Computer Graphics."

Lightwolf
09-05-2006, 11:24 AM
My question is, after reading what I posted below, has Lightwave 9 added vertex normal data?

Nope, it hasn't. I've been asking for that for ages as well. As a side note, he's not _quite_ right, smoothing angles are set on a per surface basis in LW, not a per mesh basis. For the purpose of CAD conversion there is little difference though.

Cheers,
Mike - who prefers 15°

wizlon
09-05-2006, 11:32 AM
Thanks Mike. We use between 5 and 25 degrees but nothing is working that well.

We are currently rendering highly reflective metal surfaces on a lot of our projects and it's really showing up the errors. Also refraction issues cause us to remodel all tranparent data, which is very time consuming.

Cheers.

Lee.