Wikipedia:Picture peer review/File:Bump map vs isosurface.png

Bump map vs isosurface

Original - In ray traced images, bump maps are used to simulate bumps, wrinkles and dents on a surface by changing the way that surface appears to be illuminated. The technique is limited in that it does not actually modify the shape of the underlying object. The sphere to the left has had a bump map applied to simulate a crumbling surface, but neither the sphere's outline nor its shadow are affected. The sphere to the right uses a similar bump map as an isosurface function to actually modify the size and shape of the underlying sphere. Both the outline and the shadow are affected.

Version 2 - In ray traced images, bump maps are used to simulate bumps, wrinkles and dents on a surface by changing the way that surface appears to be illuminated. The technique is limited in that it does not actually modify the shape of the underlying object. The sphere to the left has had a bump map applied to simulate a crumbling surface, but neither the sphere's outline nor its shadow are affected. The sphere to the right uses a similar bump map as an isosurface function to actually modify the size and shape of the underlying sphere. Both the outline and the shadow are affected.

Long version starts here: I've done some minor tidying to the article on bump mapping recently, including sourcing the key problem or limitation with the technique that shapes given a bump map only LOOK like they've got a bumpy surface because of the way they reflect light. The shape itself isn't actually changed. This is important because it can cause problems with obtaining realism in bump mapped images but I was unable to find an image which actually showed this important limitation clearly; so I created this one. I know it's early days for VP, but I think the encyclopaedic value should be clear and I might as well get feedback on it now. I hope there's also a chance for FP.

Some technical background about the image: it has been raytraced using POV-Ray at a high quality using effects such as radiosity (to improve the realism of the ambient lighting) and fog (to soften the background and create the mottled light pattern on the ground). This makes the "fake" CG appearance of the left hand, bump mapped sphere all the more obvious sitting next to the right hand, isosurface sphere.

Short version starts here: High quality ray traced image showing an important, and therefore encyclopaedically valuable, limitation in bump mapping by comparing a bump mapped sphere (left) with a sphere that actually has a bumpy surface (right).

Articles this image appears in

Bump mapping

Creator

GDallimore (Talk)

Suggested by

GDallimore (Talk) 21:30, 10 October 2010 (UTC)

Comments

• Version 2 added with improved bump map to show that the technique can give very good effects. Also, I have increased the similarity between the surface texture of the two spheres for easier comparison. Also, slightly increased lighting from the front but higher contrast. Any comments on either version before I submit to FP? GDallimore (Talk) 12:15, 22 October 2010 (UTC)

Seconder

• Interesting and the digital imagery is very good. I can barely wrap my head around what this is (a technique of digital reproduction of a surface?) but yes, I think it could maybe pass. However, I gotta say Ray tracing (graphics) has a lot of very good images. --I'ḏ♥One 21:54, 19 October 2010 (UTC)
  • Thanks, and I agree there's already some great stuff out there. The thing about this image is that it isn't intended to be ultra-high quality - it's intended to be highly encyclopedic with at least some artistic quality. I've been working on some artistic improvements, though, and am ready to do a new version if I get any suggestions for improvements. GDallimore (Talk) 15:04, 20 October 2010 (UTC)