Environment reflection

[noouch]

Last time I did arch rendering, I just snapped photos of a stretch of street, stitched them together to give a stretch of about 50-75 meters, gave them an alpha map to omit the sky and mapped them on to planes behind the camera.
The result should be something like this: http://noouch.de/gfx/gallery/shaus1.jpg

[zmuh11]

If you are looking for trees to use in your scenes head over to turbosquid and download a few free ones. They actually have a couple of decent looking tree models that don't cost anything. Unless of course you wanted to create everything on your own :)

Peace
Zmuh11

[aliceinchains]

I`ll try with the turbosquid trees this time :) Thanks a lot
Noouch,can you explain here how you did that scene detailed?That`s very interesting and I really want to try it,but if I have to be honest,I don`t know what`s alpha maps are for...
Well,I think a lot of people will find the explanation of your arch visualization helpful :)

[noouch]

Noouch,can you explain here how you did that scene detailed?That`s very interesting and I really want to try it,but if I have to be honest,I don`t know what`s alpha maps are for...
Alpha maps generally define what part of a texture is transparent or opaque. There's a pretty good explanation here: http://www.vterrain.org/Plants/Create/

As for how the render was made: I went out in the city with a coworker, armed with a camera and mirror ball (and respective tripods). The sky is an HDRI we shot of a similar city environment, but we found that the reflections it gave were terrible for everything other than the sky.
The lighting is the HDRI plus an additional directional light for the sun (photographed HDRIs normally don't capture the full brightness of the sun).

The actual reflections of the buildings/trees are just planes with photographs of the opposite side of the street, edited in photoshop for the alpha map and to create a panoramic image.
Another thing that helps is if you give your windows a slight bump map, since glass windows are almost never perfectly flat.

Hope this answers your questions :)

[aliceinchains]

That`s really nice :) Would you tell me is in what format you save pictures for aplha channel?I tried with TIFF and TGA,following the explanation from the site,so I made the alpha channel for the selection,I saved the file and then I used it in the diffuse and opacity channels.But nothing-so I`m doing something wrong,but I can`t find what exactly it is.

[Youpi]

Hello.

Technically, there is no flat glass. Glass is one of the most soft material I know : even with a finger, you can bend it, and it’s own weight bends it.

So, for having a good glass, always put a light low frequency fractal bump noise.

The problem with glass shaders is that they are often … transparent ! Usually, when you are watching a building, you can’t see through the glass.

So, when I’m doing architectural visualization of exterior of building, I use a ‘Fresnel’ reflection with no transparency. What is very nice is that I don’t need to model the interior !

Indeed, If you want to see the interior, you should have a correct balance of Interior / interior lighting.

Do you have an example of what kind of glass you need ?

[aliceinchains]

I want to achieve reflections like these:
http://img145.imageshack.us/img145/4121/todal01hv3.th.jpg (http://img145.imageshack.us/my.php?image=todal01hv3.jpg)http://img145.imageshack.us/images/thpix.gif (http://g.imageshack.us/thpix.php)
Have you any idea how is this made?I tried with HDRI,with plane behind the camera,but that`s not the way.

[Youpi]

Hello.

Nice ref pic. Indeed, it's CG and not a photo. In my opinion, copying CG for CG is getting farther and farther from realistic picture.

You should try to find a HDRI environment map and use it as environment (with spherical environment ! or you'll see it as background !). The environment map are better than flat planes for reflection.

In Max 2009 you have a Mental Ray shader to have a different image for background and reflection. Surely it would help.

You can try with the wonderful free HDR sample environment from HDRI Location. It's a little bit big, but results are really awesome !
If you don't have enough RAM, you can downsize it with Photoshop.

here it is : HDRI location Sample (http://www.hdri-locations.com/freesample.php)

You should also have a little bump on our windows.

Often for architectural picture, I use the HDRI skies from Parthenon project, from Debevec.org
Thanks to this nice work, you can choose the hour of your HDRI environment.

Post your result !

[aliceinchains]

Well,that`s the result for tonight.I`ve been working on this for three days now,and still the same problem appears to me-i can`t get any reflections,no matter how hard I try :)
http://img246.imageshack.us/img246/2899/1wipgh3.th.jpg (http://img246.imageshack.us/my.php?image=1wipgh3.jpg)http://img246.imageshack.us/images/thpix.gif (http://g.imageshack.us/thpix.php)
That`s the house I see from my terrace here.I toke some pictures of it,and in them the windows actually acted like mirrors-only reflecting,completely opacity objects.So I tried with mirrors,but again it didn`t work.I just now tried with the HDRI.I put a HDRI with spherical environment in the Vray environment slot,and again...it`s the same.When I put the HDRI in the Max environment slot(rendering-environment) it appears in the backgroung.I tried with a lot of planes behind the camera.Nothing.
I know that I`m doing something wrong,but I cant understand what is it.As you can see in this picture,the glasses are relfecting only the tiles,although there`s a vray environment HDRI map.But I learned how to make alpha maps and use them :) That`s really useful.

I posted that CG work only to show what exactly I want to achieve.Sure real photos are better example :)
And last-I`m making attemps to use 3ds max for only 6 months...so I think not everything is lost :)
Have a nice day

[noouch]

The model and shaders look fine (except you may want to add a little more bump on the windows explanation on why flat reflections look dull here: http://www.neilblevins.com/cg_education/flat_metallic_surfaces/flat_metallic_surfaces.htm ). In any case, HDRI environments are not really a good solution for reflections in windows. It's more a question of putting reflective billboards in the right place.

It will probably take a bit of experimentation, but eventually you'll find out where to place billboards so they reflect in your windows. After that, all you need to do is give the billboard a texture to reflect. On the image you show, it even looks like there's a bit of fakery going on.

...maybe it would be helpful if you posted your scene or at least a view from someplace other than the camera?

[aliceinchains]

Just one question-what bump map should I use for the glass?

[Johnny_Cannuck]

Render in multiple passes. Render your building without glass, then render only the glass with a backgroud shader on the rest of your building. This will let you play around with them in comp - don't try to achieve perfection in your 3D renders because you'l only frustrate yourself. Also a simple solution for blurring reflections is to use out a blurred version of the HDR image for the reflection pass. You can even reduce the images dimensions to as small as 256x256. You'll get the look you want and it'll take you far less time.

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