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Jagged nurb?
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Jagged nurb? // Archive: Tech Forum
Post by splinters // Sep 18, 2007, 9:27pm
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splinters
Total Posts: 4148
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Yeah weird title I know. Can't get my head around the problem here.
Take a look at this image:
http://forums1.caligari.com/trueSpace/attachment.php?attachmentid=8489&stc=1&d=1190158398
The string on the table is a nurb made from a circle and a path (loft tool I think). Anyway, it look fine in realtime and is nice and smooth but when I render it is jagged. I checked triangulation was on and that the material painted was not faceted but otherwise I am baffled.
I am using Vray from the model side with bridge enabled (obviously) and have used this method before for a Vray images of straws which worked very well but I have no idea what the problem is this time.
Also, it appears to be 'flattened' in one place as well....again, no idea why but it is only at render time.
Any ideas folks? |
Post by classic12 // Sep 18, 2007, 10:51pm
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classic12
Total Posts: 243
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i did something like this yesterday by just making a cylinder and then extruding and smoothing... it looked okay for me in the render so may work for you? i dunno ill make an example
Ive done an example i dunno if this is what your looking for or what but all i did was
draw a cylnder rotate to the point i wanted it to start at and extrude the end and rotate to the shape i wanted.. then added 2 on the "add ss" button..
Image 1: http://img294.imageshack.us/img294/7154/wireys9.jpg
image 2: http://img214.imageshack.us/img214/1081/wire2qe8.jpg
image 3: http://img294.imageshack.us/img294/7537/wire3gy0.jpg |
Post by Nez // Sep 18, 2007, 11:01pm
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Nez
Total Posts: 1102
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That is a weird one; obviously, only being in TS5 I can't really comment on the specifics of the problem. My experience of lofting (and even lathing) in TS5 has often driven me to distraction. The odd thing is the shape shown could be the equivalent of a non-subdivided geometry required to produce a string?
Which brings me to my suggestion - rather tha nlofting, could you just sweep a simple profile along a 'zig-zag' path and off the table edge, and then just subdivide to give you your string instead? Doesn't resolve the problem, but ought to work as an alternative? How have you formed the string in the other images from the story?
Sorry I can't be more help - it's times like this when I wished I had TS7.5 so I could be more relevant! But I don't think my feeble old home PC would be able to handle it... |
Post by Nez // Sep 18, 2007, 11:10pm
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Nez
Total Posts: 1102
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For the benefit of those few who don't know what I'm talking about (I realise you do, of course, Splinters!) I have attached an image. Classic - this is similar to what you've done, except I haven't bothered to start with a cylinder as it's not entirely necessary...
I only really started to look at SDS in the last few months and wish I had earlier, so cool...
However, none of this solves why what Splinters has got currently isn't working properly:confused: |
Post by classic12 // Sep 18, 2007, 11:18pm
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classic12
Total Posts: 243
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I didn't no you could do that :) but i found it pretty simple to do the table scene thing with the cylinder within about 1 min or so .. just trying to find a solution for him |
Post by splinters // Sep 19, 2007, 12:02am
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splinters
Total Posts: 4148
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The beauty of my method is I can change the circle profile or the points on the path and the string updates accordingly. Using a sweep method is less flexible.
Also, I render this in LW and it is perfect, using Vray is causing the problem. |
Post by splinters // Sep 19, 2007, 12:05am
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splinters
Total Posts: 4148
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I think I am answering my own question here. This is Nurb based and Vray does not support Nurbs yet. Not sure what exactly is happening with the bridge here as it also looks fine in model side...it is only at render time that it becomes jagged.
Looks like I will have to convert to a poly and use SDS prior to render, remember to save the object beforehand if I have to change the path again later....shame Vray can't do this though...:o |
Post by classic12 // Sep 19, 2007, 12:28am
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classic12
Total Posts: 243
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:( my method is stupid lol! hope you fix it. |
Post by Jack Edwards // Sep 19, 2007, 9:09am
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Jack Edwards
Total Posts: 4062
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Right clicking on the convert Nurbs to Polyhedra tool brings up the conversion options. I think these are what the bridge uses.
Another option would be to convert it to polygon then add SDS like you mentioned. :) |
Post by splinters // Sep 19, 2007, 9:40am
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splinters
Total Posts: 4148
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I will look into that Jack. When I convert it to a poly it is becoming distorted. Puzzled here, I have a string in other Vray renders for this project...problem seems to be in this one only...:o |
Post by Jack Edwards // Sep 19, 2007, 9:44am
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Jack Edwards
Total Posts: 4062
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Maybe it is just a difference in loop density in your Nurbs object? :confused: |
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