HI I am pretty new to the whole rendering process ...

I am starting to try to render skin with bump map applied.

Can anyone tell me why, when a gray scale of the regular skin  texture map is used, I am getting crazy black ruts in the rendrered image?

I should tell you that this is a very dumb-ass simple settings firefly render, yes there is ray tracing ( slightly)

The funny thing is, I way way modified the black and white levels of my particular area I was working on  (nipple) and it came out OK -  but the rest of the body, like near throat and between breasts, has the crazy dark ruts - and in those areas it is just a gray scale of the regular text map ( probably extremely close to plain  127/127/127 for most of the skin)

Thanks

Oh yeah BTW  does anyone know how to force the attached image to be BELOW  the text in a post?

Thanks

Last things first.

To put an image in a forum post in the text itself, use the "image" button of the editor. It'll place the image at the current text insertion point.
Note: you'll have to host those images somewhere, they are NOT uploaded to the 'rosity servers! So you either have to have them on your own site, or hosted on photobucket or some place like that.

Now for the bump. I suspect you're not using bump - you're using displacement. Displacement actually "displaces" geometry, while bump just gives the illusion of raised/lowered parts.
If you're using displacement, chances are that a pixel gets pushed beyond the displacement bounds set on the object itself. In that case, it won't get rendered: it'll be black.
Solution: set the Minimum Displacement Bounds value in the Render settings to something more than zero. A value of 2 or 3 probably will do the trick.

You should also be aware that for Poser, 0/0/0 means no bump/no displacemnt. 127/127/127 means half the maximum bump/displacement outwards.
To have inward displacment/bump, use a Math node to subtract the value 0.5 from the image map. You won't have to convert the map to grayscale yourself, the Math node will do that for you.

I hope you're aware that generating bump/displacement from a texture map is in no way an accurate method of creating bump maps. You're using the assumption that lighter colored parts of the skin are raised, and darker colored parts are depressed - which will be wrong in the case of painted on body hair or eyebrows, but would be more or less correct in other places.
A decent bump map or displacement map needs to be an image of its own. There's no simple direct relationship between a texture map and a bump map.

Thanks svdl 
I will start looking into displacememnt settings.

Yes  I agree, grayscaling the skin text map in hopes of creating a bump map is in many cases going to give you the reverse of the desired affect -

I should point out that my only reason for doing that was to provide something for the plain skin area of the figure around the nipple while I was experimenting on the nipple - and then my question arose when I saw the results - God knows WHAT I was going to do at a later point when I needed a real bump map for the whole body.

BTW earlier I had created a hand-made bump map for JUST the nipple, and because G2 figures have one giant text map for the whole bady, I made this "nipple only"  bump map  as a transparent background tif , transparency for all of the body except the nipple,so that hopefully only the nipple would be affected., i.e. the rest of the body should recieve no info from the image,  and Poser did appear to in fact considerthe transparency as a nuetral gray- if you can believe the preview window. ( I still had the same ungly black patches)

AS U CAN SEE i know NOTHING about rendering.

I will work more on paying attention to displacement

Thanks for the advice. I have much fiddlin' to do.

You might want to take a look at the VSS thread http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2737823. Warning - it's long, and quite technical. But it contains links to a fantastic free tool to create more realistic skin on ANY character - it's not tied to Victoria 4 or Apollo or Sydney or - you name it.

Attached Link: Question about displacement

The thread started out asking about displacement. But near the bottom of Page 1 we started talking about the same problems showing up in bump as well.

Exactly what you see here is being explained in that thread.

When you have a bump map with very little dynamic range, nearly all mid-gray, and you crank the bump level up to make it do something more visibly, you end up moving (virtually) the whole surface really far. Mid-gray is NOT neutral.

"and Poser did appear to in fact considerthe transparency as a nuetral gray"

In Poser, gray is never neutral. That is a myth, conjured up constantly despite my demonstrating otherwise at least 20 times in the last two years.

Please read the linked thread - study the images, and then spread the word. You'll save yourself and a lot of other people a ton of grief if you remember to NEVER EVER use the phrase "neutral gray" again. The correct phrase is "neutral black".

OT: BB, I thought you were off skiing?

and if you want to depress something with your map (as one occasionally does), you can use a math node to subtract.  subtract 0.5 from a greyscale map will make mid-grey = 0, black = -0.5 and white = 0.5.

Quote - OT: BB, I thought you were off skiing?

Too cold. -22 Fahrenheit.

OW!

Bagginsbill .

Thank you for the further clarification and reference to the other thread. That thread told me a lot.
Thank you, Bagginsbill, for "going easy" on me -as far as the depth of your discussion in this thread. Obviously you are  extremely intelligent in this area.
......Sometimes when you are really cutting loose in these threads and breaking down stuff, it makes my brains hurt to read it. I become quite full of fear, or fright, or what have you.
Its like you are bringing people to such a micro level of enlightenment, that we are approaching possibly causing a tear in the fabric of the space-time continuim, or maybe opening up a crazy black hole, or forming anti-matter  or some such.

For now, I will stick with " BLACK  is "nuetral"   AND as black becomes lighter, you get further displacement "  That is what I'm going with  as I look into this further. Some day I will be able to have discussion on a much higher level with you peoples here at Rendo.

Thanks!

Oh, now you're being silly. Everybody knows you can't make anti-matter just by talking. You have to wave your hands, too.