New batch of Gnomon DVDs (inlcudes GI with Vray)

[cpnichols]

actually he didnt say a point light he said a direct light. which is what i use for my sun. for a vray area light to be accurate you need to make it the size of the sun and move it as far as way as the sun is. pretty much impossible to do. a direct light is more accurate.

In the voice of Lambarg from "Office Space": hhmmmmm.... yeah... I'm going to have to go ahead and disagree with you on this one... The light that is emmited from the direct light is from a point, not an area. That is what I mean. I did not mean an omni light. Plus the sun is not a point, it is a disk in the sky. A disk of around 2 degrees over the 180 degrees of the sky (according to Debevec). Atmospheric effects can enhance this. This is more important to me then using a direct light. Area shadows are only one part of the process, illumination and specular are the key elements that I am looking for in Vray lights when using it for a sun. So direct lights are just as flawed as area lights (for different reasons).

I choose area lights for sun because: a) vray kicks ass and can do area lights really well. b) it looks better to me, and therefore is an artistic choice

[olitech]

In the voice of Lambarg from "Office Space": hhmmmmm.... yeah... I'm going to have to go ahead and disagree with you on this one...

lol...i knew it...i could've swore i kept hearing Lambarg's influence in your vid....hehe

Seriously though, i assume you turn off the decay of the vray light then...

[cpnichols]

In the voice of Lambarg from "Office Space": hhmmmmm.... yeah... I'm going to have to go ahead and disagree with you on this one...

lol...i knew it...i could've swore i kept hearing Lambarg's influence in your vid....hehe

Seriously though, i assume you turn off the decay of the vray light then...

of course... unless I want it to look like a model that I shot in a studio.

[Mirko]

Yesterday my copy of this DVD arrived! It is so great!!! Very informative!

I had the chance to view 1.5 chapters (before my wife wanted me to get of my computer). But in those chapters I have allready learned more basics about different GI techniques then ever before!

I am looking forward to you next VRay DVD!!!

Mirko

[varak]

great DVD

hai cpnichols,

I got the dvd about a weeks ago.
it's really a great tutorial and hope to see more on upcoming dvd.
well i wish the the texture map also included in the dvd so i can test with that one in movie or maybe like scene start and scene final.
Also hope to see something for architectural exterior view light setting and light baking with moving object will be consider in the future. (like walk thru)
Than image base lighting for architectral exterior like high rise bulinding.

other than that it's really a good and great dvd for beginner like me.

varak.

[Da_elf]

.....The light that is emmited from the direct light is from a point, not an area. That is what I mean...... Plus the sun is not a point, it is a disk in the sky. A disk of around 2 degrees over the 180 degrees of the sky (according to Debevec).

Ummm. did paul debevec ever study anything to do with natural science rather than just physics?
lets see. the sun has a diameter of 1.4 million km. it is 146 million km away from earth. (or us away from it) So im not entirely sure how paul could possibly think the sun is in the sky unless he is from an ancient civilisation. Point lights are where light eminates fron a single point and move outwards from it. like an omni. A direct light will more accuretly capture the paralel light we get from the sun. a vray area light is an area point light. rays will come out from it none paralel. with a direct light you just turn on area shadow to get what you need from the shadows. For reflections i tend to attach a flat disk to direct light with a radial gradient on it using output map to control brightness of the disk. naturally the disk is set not to reicieve or generate GI.

[percydaman]

i think you guys are splitting hairs here... sure if you use a vray light, technically your shadows wont be 100% parallel, but then are the suns shadows truly 100% parallel? And is it even worth noticing?

[Da_elf]

well. basically if you were working on a scene where the sun was comming from the side of a couple of objects in a row then you will notice bigtime

O Sun as a vray light


O1 O2 O3

you will notice the difference in shadow in this with the shadows on O1 and O3 going in oposite directoins. this is really close though. but in order to get those shadows more or less paralel then you have to move the vray light really far from those objects. otherwise you wont get paralel results.

[Syclone1]

hey Elf it could be my monitor or you have the Envionment cranked up a little to much but no matter how hard I look I cant see any shadows on 01, 02 or 03....

-dave

[Da_elf]

well. i didnt draw it in in asci but if you trace a line from the point light (vray light) to the objects you can see the shadows would go in different directions. i didnt wanna do an image to represent this since i was lazy hehe. im just curious how far cpnichols need to put his sun to defeat this effect

[cpnichols]

Elf... let me clarify... I know we can agree on this.... or at least agree to disagree. And don't dis Paul.... he has forgot more about light than you or I could ever know... Plus he is a friend of mine. The Sun does indeed give essentially parallel shadows. In this way, the area light I am using has some flawed. I agree with you on that. And so would Paul if he was arround. But from the point of view that I am using it, I don't think that it is that noticable. The sun is also a disk in the sky (not a singilarity of light). Omni lights, Spot Lights, Direct Lights, all shoot light from a single point in 3d space, and therefore are point lights as opposed to area lights. Now I do use those lights as well, but when the only light source is the Sun, I like to use an area light so that it gives the light source more life in terms of diffuse, specular and its shadows... all at once. In that way, the sun emmits lights (and reflections) from several sampled areas (from Vrays POV). It is a richer light source IMHO, and I think I am fairly happy with the results. I am sure that Direct lights and Disks work great for you, and that is your artistic choice, and probably a good one. I hope that the images that I have provided will prove that area lights can be used for sun light.

Now come here and give me a hug... no wait... Let me go the Barbados! Then I can go fishing after....

[Da_elf]

actually it wasnt a dis to paul seeing as how he has played a huge roll in lighting. im just curious though how far away from your scene do you put your light. i used to try vray lights but i found unless i put it really far away i would get the shadow errors and when i did put it far away i needed to tweek some things to get the shadow working correctly. sometimes when the light source is far the shadows didnt calculate correctly. i always modeled in feet and inches. the other problem i found however was that the light was sampling everything. in all directions. with the direct light i could pull in the hotspot and falloff to encompas only what i needed to have shadows on and i assumed all this time it was saving on memory with the shadows. your images do look great. i just wanted to know more specifics on how far to put your light to get that working properly. BTW was some good barracuda fishing recently

[cpnichols]

BTW was some good barracuda fishing recently

Ah you bastard... I'm so jealous. Actually what I really want to do is go after Bonefish. Do you have that in Barbados? my wife and I need a Chrismas vacation.

As far as how far I put the sun. Far enough til it looks ok. You are right about putting light sources too far away. It can be a problem with any raytracer. Very narrow rays can cause all sortsa floatingpoint errors. Again.. it is an artist choice. In the same way that on a movie set, when you are faking the sunlight coming through the trees, you see how far you can get away with.

[Da_elf]

bonefish...hmmm..doesnt ring a bell. some of the main fish you usually see people catching at barracuda, swordfish, blue marlin, dolphin (not the mamal dolphin. this is a fish), and yummy grouper. barbados is still a cool place to visit though

[TRGraphics]

Well I just ordered the dvd as well!

Has anyone tried playing this in a standalone dvd player attached to a large screen tv? I hope it works.

Tony