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Colour use - Chris Beckett - 2012-10-11

This is a repost of something I just put up on Flickr. Hopefully this image works; if not, the link to Brickshelf should at least be active...

[Image: colours_complete.png]

Here is something that has been bugging me for ages, and I was wondering if anyone could shed some light on it.

These images show the POV-Ray output for various rendering conditions. Three colour definitions are used - MLCAD standard, LGEO and Koyan's list. For the standard MLCAD colours, POV-Ray checks the list of pre-defined colours (I am assuming this – please correct me if wrong) and uses those, leaving everything else as “color 7” (lt grey). For example, the reddish brown and lt flesh plates are both lt grey, as these are newer colours and not on the standard list. For the modified “solid” and “24-bit” colours, POV-Ray defines each colour itself, rather than referring to a list, so every colour is included. The down side is that they do not look very realistic in POV-Ray, with the exception of the 24 bit colours (I have been using these recently).

When using LGEO, POV-Ray first checks each colour against LGEO's list and then defines that colour if it is not there. However, having done this, it goes on to associate “color 7” with those parts which have colours not on the MLCAD standard list, even though new definitions are available. Again, this can be seen for the reddish brown and lt flesh plates. The same thing happens if you use the “koyancolours” file – apparently all it does is redefine the colours on the standard list, even though it includes many more. Adding new colours to the list does not work, but reassociating existing colours to ones that are not working (e.g. changing a bizzare purple to lt flesh and calling the bizzare purple colour code) does work – the lt flesh plate is now the right colour. Now for the weird bit – if you go into the POV-Ray file and change the remaining “color 7” tags (Koyan added reddish brown to his list, so this plate is no longer an issue) to colours on the koyancolours list, which were the originally intended ones, they come out fine. The case here is the lt and dk bley, colours 71 and 72 – these do not work in standard MLCAD, LGEO or unmodified POV files for koyancolours.

In short, does anyone know why on earth this is happening, or is this a more general concern for how MLCAD does its thing?

Many thanks,

Chris


Re: Colour use - Philippe Hurbain - 2012-10-11

A few questions first, I guess someone with more knowledge of Povray than I have will answer...
- What MLCad version do you use?
- Do you have latest ldconfig.ldr installed?
- What do you use for LDraw -> pov conversion?
Otherwise, your image doesn't work because your Brickshelf folder is not yet public. Could you provide a deeplink in the meantime? (deeplink how-to here)


Re: Colour use - Chris Beckett - 2012-10-11

Hi,

Sorry, should have included this information before. I am using:

MLCAD v 3.4 (latest), with latest ldconfig (all installed using the new all-in-one installer)
POV-Ray RC 6 (not the latest but RC 8 is very similar)

The computer has just been formatted, so there is no possibility of older versions of these files lingering in the system.

To convert between MLCAD and POV-Ray I simply export the files to a folder and then use L3PAO to generate the .pov file from the exported MLCAD document (by exporting, it removes all references to submodels, which L3PAO cannot handle). This was a method I worked out myself, so it might be the cause of the problem...

Apologies for the poor image link - the URL was to the folder, not the image (I used to make exactly the same mistake on the Classic Space forums, all those years ago). Now fixed.


Re: Colour use - Philippe Hurbain - 2012-10-11

Chris Beckett Wrote:To convert between MLCAD and POV-Ray I simply export the files to a folder and then use L3PAO to generate the .pov file from the exported MLCAD document (by exporting, it removes all references to submodels, which L3PAO cannot handle). This was a method I worked out myself, so it might be the cause of the problem...
Have you tried LDView Pov export?


Re: Colour use - Travis Cobbs - 2012-10-11

As long as LDView is configured to use LDConfig.ldr (which it is by default), LDView's default color output for POV export should match what is in LDConfig.ldr. Note: the option is "Process ldconfig.ldr" in the Colors box of the General tab in LDView's Preferences dialog.


Re: Colour use - Max Martin Richter - 2012-10-11

I had the same problem with the "newer" colours. I got everytime a lt. gray result.
But I don't know what I did, it works now on my computer.
There is something in my head, that I changed something in LDraw.ini
Nevertheless nowadays I use only Ldraw for the export.

Martin


Re: Colour use - Chris Beckett - 2012-10-12

I'll give LDView a try as an exporter, and see if I can get the colours to work. Thanks for the tips!


Re: Colour use - Chris Beckett - 2012-10-13

Hi,

I tried the LDView export function, but ran into a few errors. Firstly, the render wouldn't run, as the language version wasn't correct for lg_defs. I corrected this (I think) by including the line "version 3.1" (no quotes). The render then ran, but none of the pieces were visible (LDView version first, resulting POV-Ray image second):

[Image: ldview_01.png]

[Image: ldview_02.png]

Any idea why this might be happening? The parts are declared in the .pov file (as far as I can tell). Interestingly, this .pov file contains all of the correct colour definitions, so it is a stage further on than the MLCAD export errors I began this thread with.

Thank again everyone,

Chris


Re: Colour use - Steffen - 2012-10-13

can you please attach the resulting pov file here?
I'm wondering if maybe hits you...


Re: Colour use - Chris Beckett - 2012-10-15

Hi Steffen,

Sure thing - I'll post it as soon as I get back to the right computer. The second issue sounds the more likely, as the .pov renders (although without displaying anything) with the added "version 3.1" line - no \48 problems are reported as errors (although maybe as warnings? I haven't checked out the warnings dialogue). Thanks for all the help!

Chris