Advice needed on my first Add-on

[meegja]

Okay, here is my first Add-on: http://www.3dart4u.com/celestia/RT_52.zip , the RT_52 galaxy. Just some fantasy galaxy
But I still can not figure out on how to get my textures brighter. Other (real) objects/nebulas are way brighter?
I made this one also bright (I use Photoshop), but when in Celestia it's dull ... how can I make it "sparkle" more?
I did test the RT_52.zip in latest beta of Celestia. If anyone can make it brighter, please be my guest and please tell me how it's done?

[selden]

Meegja,

Your image needs to be completely opaque in the areas where you want the brightest colors. According to the ImageMagick "identify" program, your png image has a "Matte Color" of grey75. This makes the entire image slightly transparent.

In other words, you need to create an Alpha channel matte for your png image which has values ranging from black (where you want the image to be completely transparent) to white (where you want the image to be completely opaque).

I don't know what the appropriate techniques would be in Photoshop. I use a much simpler paint program to create a separate 8bit grey-scale image whan I want a detailed Alpha channel. I then use a utility like NetPNG's pnmtopng or ImageMagick's composite to insert the grey scale image as an alpha channel in a color png image.

Does this help?

[meegja]

Thanx Selden!! It helps, yes and no. The programs you mention are all abracadabra for me. ImageMagick sounds interesting but after downloading and looking at it, I really didn't know how to handle 1 letter extensions? I am a pure Windows user, who is used to EXE and so on
But as I understand now, there has to be a mask / alpha channel. I just do not know how to put that in a PNG .... ah well, I keep on searching. And also keeping busy with my first Add on

[selden]

Never mind.

I just followed my own advice and got just as dim an image as you did. (Having no alpha channel is the same as having one that's all white: the picture is opaque.)

I then used a trivial 3DS model of a flattened cube created using Anim8or and the image was bright.

In other words, there's something in your model which is making the image dim.

When I use Anim8or to look at the model, I don't see anything out of the ordinary with the surface material definition: Anim8or shows the same values for properties like "Ambient" and "Diffuse" as it does for materials on models that are bright.

Unfortunately, my knowledge of 3D modelling is essentially zero, so someone else will have to help more.

[Rassilon]

The best way to create transparent textures is making a Targa in Photoshop and turn it into a PNG in the Gimp...

Make an alpha channel with whites as solid and blacks as transparent...I tend to turn the image grey and paste it into the alpha channel...Save as 32 bit TGA and open the Gimp...Right click when in Gimp on the image and save as PNG...In photoshop its not recommended to do this as the alpha turns white when saved...

Unless someone has a better method, thats the only way I know of making the best transparent textures...

For 3ds files make sure before exporting that the diffuse channel of the objects texture is white and the opaque channel is at 99% with both filled with the above texture as is...

[meegja]

I found it!!! It was indeed related on how the texture was used on the 3DS object and the conversion of it. Testure is now bright. No luck on the transparacy though, even not with TheGimp. Seems that a 3DS object always will be transparent, no matter what.
Okay, that is sorted plus that I manged to line up a bundle of stars along the gallexy ... was a bit of a struggle but I won!!
Updated Add On on http://www.3dart4u.com/celestia/RT_52.zip
Thanx everybody in advance for the advice!!! Comment/suggestions on my first Add on are always welcome!
And here is an image of the RT_52 galaxy:

[don]

Howdy Menno,

All of you artsy / graphics / 3-D modeling folks simply amaze me. This looks really cool!!!

I am glad you won the struggle.

Thank you Menno!