Contour map gray resolution

[liquidguitars]

I think it's better to change the image map file from index to RGB and then inport into designer as a 24 bit after bluring.

LG

[santhony94107]

I use PaintShop Pro (have used it since version 1) which has a "blur" function as well. I used blur->color averaging and almost all the steps disappeared. The remaining ones were so inconsequential that they sanded out very easily.

Thanks for all the suggestions.

Scott Anthony

[Gman_Ind]

The designer does use the 256 heights, I believe more shades will just result in a smoother transition, If he can export up to 1024 shades it should be very smooth even thought designer is using 256 of the colors. and without secondary work. IMHO

[liquidguitars]

This is my feeling two, designer works way better in 24 bit
Some early software did not like 24 bit images for bump mapping as it was more than needed, Designer can read color 0
In an 8 bit image but also reads 32 alpha, thus will remove the background square without manually raising or lowering the z value.

LG

[cycollins]

...but there may be a way to ameliorate the stair-stepping effect. BTW I'm an Amiga user of old myself, so that makes us part of an arcane brotherhood. Years ago at Electronic Arts, I worked on the 3DO game platform (also developed by Jay Miner of Amiga fame). For obscure reasons, I needed a way of smoothly interpolating 16 shades of gray across a quad (256X256), with one 4-bit value at each corner. I won't go into all the details of how it worked, but the key idea was to use a noise function to distribute the values, so that it appeared to be smoothly interpolated. I don't mean to be negative, but I don't think the blurring filter will help you very much, unless you're not already making good use of the 256-value space (i.e. normalizing your height-field from 0-255). Your source image is already smooth. Bluring will only change your contours and ultimately the whole thing will only be re-sampled at 8-bits per pixel anyway. Here's one alternative: when you create your height-map from your theoretical contours, create it as a 2D array of 32-bit unsigned values. I'm sure 16-bit values would be sufficient but just for good measure try 32-bit first. Write this image out in a format that allows 32-bit grays (I think TIFF can support this, PGM does but be careful of endian-ness and D3D texture formats are easy to write and support 32-bit grays). Then read this into Photoshop (which recognizes the above formats - can't say about Paint Shop Pro - one of my favorite apps but I haven't used it in years, since I toil for Adobe now). You should see a nice smooth image - no stair stepping. Now use the "Image" menu and under "Mode" you will see an option to reduce the bit-depth of your gray-scale image. Choose 8-bit and you will be presented with a dialog, giving you options for what kind of dithering you want to use produce an 8-bit image. It doesn't matter too much which one you choose, so you should experiment, but initially, you should just try the default which is "Exposure and Gamma" with default values. You will probably see no appreciable difference in your image, but if you zoom in very far, you will see noisy combinations of 8-bit gray-scale values, making up the surface of your guitar-back. You can now save this object as an 8-bit grayscale BMP file. Your aliasing is still there, but its influence is spread out stocastically over the surface of your object. When you go to carve the object, that noise will be lost in the grain of the wood and other small inaccuracies that creep into these kinds of physical processes. When you sand the object, it will be gone forever. I've included a processed version of your gutar-back image with this post, so you can see the quality of the output (I actually just stepped up the sample size on your example, did a "surface blur" and then followed the above procedure to get the final version). It has some artifacts due to the way I made it, but the gross stair-stepping is gone, while the image remains 8-bit. You can download the example from (I can't get the attachment thing to work)

http://www.woodenyou.com/cycollins/guitar_back2.bmp

I hope this works for you (because actually I have this problem too - I just thought of this technique on-the-fly and I'm interested in trying it out as well). If you have any questions, you can PM me and we can talk.

Best of luck,
Cycollins

[liquidguitars]

I got to meet Jay Miner of Amiga fame and shake his hand. He was getting on up in age and in a wheel chair.

It’s one of my proud moments of computers. I wonder if he had an idea
how his game con changed the world.

Still not sure about designer only using 256 as designer handles and blends the PTN so well.. mesh or Voxel...

stocastically is my new cool word for the day!
LG

[Reset]

...but there may be a way to ameliorate the stair-stepping effect. BTW I'm an Amiga user of old myself, so that makes us part of an arcane brotherhood. Years ago at Electronic Arts, I worked on the 3DO game platform (also developed by Jay Miner of Amiga fame). For obscure reasons, I needed a way of smoothly interpolating 16 shades of gray across a quad (256X256), with one 4-bit value at each corner. I won't go into all the details of how it worked, but the key idea was to use a noise function to distribute the values, so that it appeared to be smoothly interpolated. I don't mean to be negative, but I don't think the blurring filter will help you very much, unless you're not already making good use of the 256-value space (i.e. normalizing your height-field from 0-255). Your source image is already smooth. Bluring will only change your contours and ultimately the whole thing will only be re-sampled at 8-bits per pixel anyway. Here's one alternative: when you create your height-map from your theoretical contours, create it as a 2D array of 32-bit unsigned values. I'm sure 16-bit values would be sufficient but just for good measure try 32-bit first. Write this image out in a format that allows 32-bit grays (I think TIFF can support this, PGM does but be careful of endian-ness and D3D texture formats are easy to write and support 32-bit grays). Then read this into Photoshop (which recognizes the above formats - can't say about Paint Shop Pro - one of my favorite apps but I haven't used it in years, since I toil for Adobe now). You should see a nice smooth image - no stair stepping. Now use the "Image" menu and under "Mode" you will see an option to reduce the bit-depth of your gray-scale image. Choose 8-bit and you will be presented with a dialog, giving you options for what kind of dithering you want to use produce an 8-bit image. It doesn't matter too much which one you choose, so you should experiment, but initially, you should just try the default which is "Exposure and Gamma" with default values. You will probably see no appreciable difference in your image, but if you zoom in very far, you will see noisy combinations of 8-bit gray-scale values, making up the surface of your guitar-back. You can now save this object as an 8-bit grayscale BMP file. Your aliasing is still there, but its influence is spread out stocastically over the surface of your object. When you go to carve the object, that noise will be lost in the grain of the wood and other small inaccuracies that creep into these kinds of physical processes. When you sand the object, it will be gone forever. I've included a processed version of your gutar-back image with this post, so you can see the quality of the output (I actually just stepped up the sample size on your example, did a "surface blur" and then followed the above procedure to get the final version). It has some artifacts due to the way I made it, but the gross stair-stepping is gone, while the image remains 8-bit. You can download the example from (I can't get the attachment thing to work)

http://www.woodenyou.com/cycollins/guitar_back2.bmp

I hope this works for you (because actually I have this problem too - I just thought of this technique on-the-fly and I'm interested in trying it out as well). If you have any questions, you can PM me and we can talk.

Best of luck,
Cycollins

What'd he say? lol

[Kenm810]

In short, -- He knows more about computers and graphics then I ever will.

[mtylerfl]

Hello Cycollins,

Could you clarify a few things?...there are a few terms that I've not heard of before...

1) "Here's one alternative: when you create your height-map from your theoretical contours, create it as a 2D array of 32-bit unsigned values."
How does one do that? I'm not familiar with the term and/or function of "unsigned values".

2) "...already making good use of the 256-value space (i.e. normalizing your height-field from 0-255)"
Could you explain how a typical user normalizes the height-field in popular graphics software programs such as CorelPaint, PhotoImpact, PhotoShop.

3) "Write this image out in a format that allows 32-bit grays (I think TIFF can support this, PGM does but be careful of endian-ness and D3D texture formats are easy to write and support 32-bit grays).
I'm not familiar with the term "write this image out" - do you mean convert the image data in some fashion, or use a "Save As" to save the file in a .tif format while specifying options for that save? Also not familiar with the term "endian-ness"

Thanks in advance for your help.

[liquidguitars]

create it as a 2D array of 32-bit unsigned values. I'm sure 16-bit values would be sufficient but just for good measure try 32-bit first.

mtylerfl,

Buy create I think he is saying "render" as to centered around 8,24 and 32 bit depth 3D rendering programs. Color space is still inportant to 2D. regarding the guitar image, I was able to change santhony94107 8 bit arch top image and smooth in 24 bit removing the stair stepping in photshop, typ a 10 min job, BTW I find the scaner software can help out my images a bit 2.



LG