using 2D trees and lighting per 3dats book

[kevin miller]

I recently purchased the 3dats book and have been trying to incorporate some of their tricks for getting better renderings from 2D tree textures. As most of you probably know, using the criss crossed mapped planes can work but the lighting of the tree images can appear questionable due to uneven lighting. One of the tricks they mention is to locate 4 direct target lights (one at each cardinal point) so that the entire scene is caught in the lighting “crossfire”. The lights are parallel to the ground and are set to not generate shadows and all objects are excluded except for the tree objects, which are selected as included under light illumination. I have tried this and it seems that no matter what settings I put in the light’s multiplier or energy parameters, I am seeing no difference in the lighting of the tree objects. I have entered 15 as a multiplier and nothing. Some have said there can be issues with the include/ exclude light option and others have said they usually just self illuminate at 100% (which is what I normally did). The problem is there seems to be several areas in the 3dats book where things do not seem to work out as well as they explain. I am a little worried since I just ordered another one of their books for over 100 dollars. I like the information and explanations so far but a couple of items never really get fully resolved which is frustrating.

 

 

Can anyone make a suggestion of what I am not doing correctly?

 

 

Thanks,

 

 

K.

[Brian Smith]

I have tried this and it seems that no matter what settings I put in the light’s multiplier or energy parameters, I am seeing no difference in the lighting of the tree objects. I have entered 15 as a multiplier and nothing.

 

Kevin,

The methods do definitely work as described and I don't know why you are getting erratic results. I have never heard of this problem before and have used this background rig for many years...as have countless others. The fact that you say that nothing happens when you enter 15 as a multiplier on your light is an indication that you are doing something that you shouldn't, but until you provide more information and/or screenshots, there's not much that anyone can help with. Perhaps if you record a short video of your scene as you render, that would make it possible to diagnose the problem properly. You could use http://goview.com/goldwyn/spring/play?method=indexPage to record your screen if you want. It's free and quick to install.

[kevin miller]

Hello Brian,

 

This is not a slam on your book as there have been countless tips that have been great and it is challenging to cover every little detail especially when things are probably second nature to you. Your book has been one of the best I have read. However, obviously I am doing something wrong and obviously it has worked for you or you would not have mentioned it in the book. But if I am not doing something right, is it possble that I am having to mess around with it since there was really no explanation on the light settings outside of the include/ exclude? I will post a screen shot but you will see no lighting difference on the tree object so that seems pointless. Maybe it would be better to post a screen shot of the light settings or maybe I will set up a scene with just a tree object and try it with one light. All I am trying to do is explain the fact I am not getting the desired results.

 

If you want to know of another example, the discussion on background envirments in mental ray is another. At no point do you mention the fact that you need to really dial up the settings in order to see the background render in the enviroment map, otherwise you get nothing when you render. This is also missed in another author's book I have. Somemone in another forum had to point this out to me before I actually got some decent results. Nobody is perfect but it is frustrating trying to accomplish something by instructions when there are some holes in the instructions, especially book instructions.

[Tommy L]

the light multiplier of 15 would be high under some circumstances but low under others. Describe your lighting setup. Im going to bet $10 that you are using vray sun and a vray physical camera. Under those conditions, 15 is a low multiplier for a non-physically based light source. Try turning off all other lights and GI and seeing if the 'tree-lights' cast any illumination. If not, keep turning them up until you see something.

[kevin miller]

I am using mental ray but your testing idea is a good thought. So simple but sometimes the simple ideas escape us since they are so obvious.

[Tommy L]

Doh! Looks like I lost $10. However, the 'strip it out and add it back in' approach is the best for trouble shooting, especially with lights.

[CJI]

It would be fair to go halfers on the 10 spot as if he's using mr physical sun and sky with exposure control its pretty much the same deal as Vray's physical sun>sky>camera setup. :-D

[Tommy L]

Yes, it always comes down to exposure in the end. Always.

[Brian Smith]

Nobody is perfect but it is frustrating trying to accomplish something by instructions when there are some holes in the instructions, especially book instructions.

 

Kevin,

Regarding the lighting of the trees, I'm confused as to exactly what page you are seeing instructions that aren't working for you. I don't think there is really even an exercise that walks you through the process of setting this up. Below is the quote from the book that describes the process. I don't know how to explain it any simpler. You can do this with any type of object and any type of light and you will get the same results.

 

"Perhaps the biggest drawback users find in creating 2D criss-cross vegetation is the poor illumination that usually plagues its use. The reason for this is because the light in the scene does not evenly illuminate the 2 polygons that make up the tree. To ensure that the illumination is even, you must first ensure that the 2D vegetation does not cast shadows on itself (as well as on anything else), and that enough lights are used to cast equal illumination in all directions around the perimeter of all trees. The first part of this is simple - just turn off the Cast Shadows and Receive Shadows option for the trees (in the Properties dialog box of each object). The 2nd part requires you to place lights around your scene that only affect the 2D trees and that cast light horizontally across the ground."

 

As far as the mental ray chapters are concerned, they were written by Chris Bullen and I can't personally validate the accuracy of them as I am not a mental ray expert. They were tech reviewed by someone outside our company. As you said no one is perfect, but I can guarantee you that the tree illumination works as described and no one else has brought either of these two issues to our attention before. The fact that you're using mental ray may be complicating the tree issue. I suggest simplifying things and first trying it in scanline to ensure the process works. If you provide additional information about what you're doing and/or screenshots, I'd be happy to take a look, but you're not really giving me much to work with by simply saying a process described in the book doesn't work.

[kevin miller]

Hello Brian,

 

Again, before I get into this, I am not overlooking the fact that your book is very well written and very helpful. With that being said, i seet up the light rig just as you described and I guess I was expecting more noticeable effects. However, I need to try some of the other suggestions others have made that do sound like they would help. Another point is, should I really be seeing a differnece when I have already set up the self illumination on the tree material?

 

Anyway, I will post my results. I am expecting to recieve your new book here in a day or two and I am looking forward to seeing the chapters on Mental Ray as wall as the other chapters.

 

Thanks,