Problems with CAD/ .dxf import

radiance-general
1

Hello @all,

1. Problem
I got Auto CAD 2005 files of studio equipment, like video monitors, edit desks etc. from a company. I want to work with them in Radiance.
The 'radout' exporter doesn't work with autocad 2005, so i got an old license for Autocad 2000. There the exporter works. But the 2005 files dont work in 2000! An exported version of .dxf files didn't work either in 2000.
I got a hint from an old mailing list article, to export the files from autocad 2005 in a .3ds format. Autocad 2000 can read this format and the 'radout' export worked. But now i have a '.rad' file with hundreds of polygons and its impossible to give them the right material, because i don't know where they belong to. If i create one material and apply it to all polygons, i can see the model.
How is it possible to get different 'layers' in the file like the body of a monitor and the screen separately ?
I have the feeling that even a simple box is subdivided in lots of polygons.
Do i have to modify may CAD files in a special way ?

2. Problem
I tried to import a 'Poser 3D' model of a character with 'dxf2rad'. I followed the instruction of the 'RwR' book on p. 422, but the command :
$ dxf2rad -i figur.dxf -orad figur
doesn't really work. When i execute:
$ dxf2rad figur.dxf figur.rad
i end up like in my first problem. I have hundreds of single polygons with no specific name and the same identifier.
I am a CAD and a Radiance starter but maybe someone can guide me.
Thanks,...

P.S. Thank you Greg for your last answer concerning color an units. I included my own display primaries now.

···

--
Christian Fusenig
Diplomand, Medientechnik
Undergraduate, Media Technology
Hamburg University Of Applied Sciences

address: Beim Schlump 27/07
              20144 Hamburg

email: [email protected]

mobile: ++49 179 5975845

2

Hello @all,

1. Problem
I got Auto CAD 2005 files of studio equipment, like video monitors,
edit desks etc. from a company. I want to work with them in Radiance.

Are they any good? Can you share them? :wink:

[details about 'radout' snipped]

But now i have a '.rad' file with hundreds of polygons and its
impossible to give them the right material, because i don't know
where they belong to. If i create one material and apply it to all
polygons, i can see the model.

I don't know 'radout' but I expect it will set the modifier
("material") according to the layer of the object. If your
CAD model had only one layer your exported *.rad will have
only one material.

How is it possible to get different 'layers' in the file
like the body of a monitor and the screen separately ?

That's a problem of AutoCAD and your model. If you have
"color" in your model when you open it in AutoCAD you can
select elements "by color" and copy/move them to a new
layer.

I have the feeling that even a simple box is subdivided in lots of
polygons. Do i have to modify may CAD files in a special way ?

Polygons (most likely triangles) are the universal "currency"
of geometry interchange. You can try to export "solids" to Radiance
primitives (dxf2rad does that iirc) but this is limited to real
spheres, cylinders etc. which are rarely used in complex objects.

You could try to find "box" entities in the CAD file and generate
a "!genbox" command for it but that will ulitmately expand to six
polygons as well (quads in this case). There is little you can do
in the DXF file.

2. Problem
I tried to import a 'Poser 3D' model of a character with 'dxf2rad'.
I followed the instruction of the 'RwR' book on p. 422, but the command :

$ dxf2rad -i figur.dxf -orad figur

doesn't really work. When i execute:

$ dxf2rad figur.dxf figur.rad

i end up like in my first problem. I have hundreds of single polygons
with no specific name and the same identifier.

You can find an online version of the man page for dxf2rad here:

     http://www.schorsch.com/download/dxf2rad/manual.html

Perhaps the two versions are different but according to this man
page your second command is correct (and works as you describe).
You can find examples near the end.

About the modifiers there is this section right at the start:

     Output primitives will have modifiers based on the layer of
     each entity in the form "l_<layer>". Floating layers within
     blocks are fully supported.

This means that you have to split elements in your CAD model
according to the desired material to different layers. If you
have a wooden chair with a leather cushion you have to copy all
elements ("faces", triangles, boxes, whatever) of the cushion
to a layer called "leather" and the rest to a layer called "wood".

Save only these two layers to the DXF file. Use dxf2rad on
this file and you will get a *.rad file with two modifiers
("materials"): "l_leather" and "l_wood".

The Radiance geometry file format requires a modifier for
each polygon so 'dxf2rad' has to make one up for the export.
It uses the layer name (as most would do if confronted with
DXF) as replacement for the material. You still have to
provide a valid definition for this material:

     # bright leather (hornbeam_wood actually :wink:
     void plastic l_leather
     0
     5 0.61 0.47 0.29 0 0

     # dark wood: elm_wood
     void plastic l_wood
     0
     5 0.46 0.27 0.13 0 0

Add these lines at the top of the file and you should
have two materials in the object.

You can find some r,g,b values on this page:

http://www.learn.londonmet.ac.uk/student/resources/radiance/material_db.shtml

hth,

Thomas

···

On 04.02.2006, at 17:44, Christian Fusenig wrote: