Member nuverian Posted January 15, 2008 Member Report Share Posted January 15, 2008 An ambient occlusion baker (radiosity) would be just great. Right now I (and maybe others) are exporting the high poly and import it in anoter package to bake the ambient occlusion..With even that feature implemented into 3DB, will make it an even better and complete software in my opinion. I know there is an ambient occlusion calculator in 3DB allready, but I am sure you understand about the type of map I am talking about.. Thats my suggestion, rather than request Quote Link to comment Share on other sites More sharing options...
Andrew Shpagin Posted January 16, 2008 Report Share Posted January 16, 2008 What is the difference between the ambient occlusion tool in 3DB and ambient occlusion tool that you are suggesting? Quote Link to comment Share on other sites More sharing options...
Member nuverian Posted January 16, 2008 Author Member Report Share Posted January 16, 2008 In 3DB tool, lights are placed around the object casting shadows.What is happening is that the arm for example casts shadows to the leg.Instead "Ambient occlusion is most often calculated by casting rays in every direction from the surface. Rays which reach the background or sky increase the brightness of the surface, whereas a ray which hits any other object contributes no illumination. As a result, points surrounded by a large amount of geometry are rendered dark, whereas points with little geometry on the visible hemisphere appear light." -(wikipedia) http://en.wikipedia.org/wiki/Ambient_occlusion That is widely used Xnormal bakes ambient occlusion among other maps as for example.. Thank you... Quote Link to comment Share on other sites More sharing options...
Andrew Shpagin Posted January 16, 2008 Report Share Posted January 16, 2008 But really what is the differelnce between "Rays which reach the background or sky increase the brightness of the surface" and "lights are placed around the object casting shadows" ? Sky is set of many lights that cast many shadows (amount of rays = amount of lights). I think that if ray from surface reaches sky then ray from the same direction from the sky reaches surface point and vice versa. Quote Link to comment Share on other sites More sharing options...
Advanced Member paulrus Posted January 16, 2008 Advanced Member Report Share Posted January 16, 2008 nuverian is very right. AO should be sampling geometry, not casting shadows. In XSI I can generate AO with no lights in the scene at all. In XSI: "Ambient occlusion is a fast and computationally inexpensive way to simulate indirect illumination. It works by firing sample rays into a predefined hemispherical region above a given point on an object's surface in order to determine the extent to which the point is blocked - or occluded - by other geometry. Once the amount of occlusion has been determined, a bright and a dark color are returned for points that are unoccluded and occluded respectively. Where the object is partially occluded the bright and dark colors are mixed in accordance with the amount of occlusion." Quote Link to comment Share on other sites More sharing options...
Member nuverian Posted January 16, 2008 Author Member Report Share Posted January 16, 2008 So...here is a quick test I did to show you what we mean... The blue circles are some spots that -in my opinion- differ in the ways that AO is calculated The red one, shows the reasons why they differ: The hand shape's shadow can be clearly seen twice casted on the leg. while in the way that people use AO this is mostly not wanted. Thats all I can explain from my point of view and not a programmers :-) By the way: A Greek lanuage is on its way...I allready start translating.That of course if you want to... Quote Link to comment Share on other sites More sharing options...
Andrew Shpagin Posted January 17, 2008 Report Share Posted January 17, 2008 Good. Thanks for explanation. Now I have understood it better. The difference is that XSI selects random rays is every point independently, so there is some dithering. 3DB selects rays in the same way in every point. In both cases artefacts will go down if you will increase rays/lights count. There is additional feature in 3DB to avoit "shadows effect" - additional smoothing of whole layer after AO calculation. About Greek language - happy to hear that! But there is soooooooooo many text in 3DB. Quote Link to comment Share on other sites More sharing options...
Member nuverian Posted January 17, 2008 Author Member Report Share Posted January 17, 2008 Well the link of wikipedia ( http://en.wikipedia.org/wiki/Ambient_occlusion ) has the mathematics about it...wich I can not understand :-) (about language...I will take my time) Quote Link to comment Share on other sites More sharing options...
Advanced Member rimasson Posted January 19, 2008 Advanced Member Report Share Posted January 19, 2008 Well the link of wikipedia ( http://en.wikipedia.org/wiki/Ambient_occlusion ) has the mathematics about it...wich I can not understand :-)(about language...I will take my time) The nice thing about Ambiant Occlusion is that you can tune the Ray dsitance used to calculate occlusion. here is an example : Occlusion Quote Link to comment Share on other sites More sharing options...
Member xrok1 Posted January 19, 2008 Member Report Share Posted January 19, 2008 it appears that 3D-brush is baking shadows not occlusion #1 3d-Brush #2 Hexagon (AO notice no shadows just AO) Quote Link to comment Share on other sites More sharing options...
Andrew Shpagin Posted January 19, 2008 Report Share Posted January 19, 2008 Plase set more lights (32-64) and smoothing (4-6) and you will get good result. If you will read the article about AO in Wikipedia you will get to know that there are 2 methods for AO calculation - random rays and casting shadows. Also notice that 3DB calculates AO for the really hight-p[oly mesh (0.5-4 m of polygons) Quote Link to comment Share on other sites More sharing options...
Member xrok1 Posted January 19, 2008 Member Report Share Posted January 19, 2008 much better, thanks check the code for your camera shorcuts. the F keys work but the buttons don't. Quote Link to comment Share on other sites More sharing options...
Member Ztreem Posted January 21, 2008 Member Report Share Posted January 21, 2008 You actually get identical results of lights placed like a sphere around your object as an occlusion shader would give, you just have to have enough lights. The benefit with a calculated occlusion shader is that it's often quicker and gives smoother result. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.