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hi

I'm a bit lost on trying to get good reflections on windows in exterior renderings. physical sky gives good results, if you don't want any clouds.
but if clouds are needed, you have to use an hdr or mxi, which leads to the following workflow:
take your sky(background image.jpg), convert it to mxi (the file size goes up 200times), make several test renders adjusting intesity until it has the same brightness as the physical sky had.
the other problem is, that you need a very highres mxi or it you will see every pixel.
is there any faster/easier way to get this?

how do other users create reflections? do you create them with photoshop in postwork or try to render them?

greets & thanks,
kami

Usually I use large reflecting planes with hdri emitters. Then I render with alpha and composite a sky in post for the BG.

BTW, you can save those LDR's out as hdr's instead of mxi's for smaller file size.

Mate you could put panels infront of the windows with simple JPG's as the reflections and hide them to the camera and also casting no shadows.

I use billboard trees that cast shadows this way to give the feel of good landscaping without taking the emphisis off the subject. It gives tree reflections in the windows even if they are between my camera and the building!

I find it important to stop the phys sky horizon reflecting in the window otherwise they are too bright!

I tried rendering with Alpha but the background is always black and when i open it up in photoshop..no way to take off the black background! What's a work around to this?

The way i take off blackground is of course use the marquee too or the magic tool..it's really annoying..and it's never CLEAN so i need to manually crop render.

PS: pm me ur contact info so i can send u sthe stuff or gimme ur msn

Nappy, you use the alpha channel render as a mask in Photoshop. It will cut out a perfect sky. If you use any selection tools to cut out the sky, you are going the wrong way!

I think there is an PS action in the goodies section for removing the alpha background.
the idea with hidden jpg planes is nice. i'm gonna try it the next time.
also the hdri-planes, but i think they need a lot of tweaking as well. but i get better control.
thank you

hey bubb,

"you use the alpha channel render as a mask in Photoshop"

How do i do this? lol

Check the "Think" site, I think there are some tutorials. Basically you add a mask to your main render layer in PS, then copy and paste the alpha into the mask.

use the action from the goodies or: open alpha image and press CTRL-A (select all) and then CTRL-C (copy), open the render image and in the channels palette menu select "new channel" --> alpha 1 . press CTRL-V (paste) and then in the layers palette select the image layer. in the select menu choose "load selection" and then select alpha 1, press on the "mask" button in the layer palette and that's it.

THX CHOO CHEE AND BUB
i will try that now...and probably fail but thx!

hey choo!

What do you mean by "open the alpha image"? do i do that in photoshop?
when I render..i check the alpha channel parameter but it only renders out 1 image? so is the render/alpha both the same image?

Do i need to render TWICE in order to get the alpha channel + render image?

no, when you check the alpha channel you get 2 images, 1 is the render and 2 is the alpha .... say your scene is called "model" then you'll get model.tga and model_alpha.tga .

read choo-chees post again.
open the alpha and rendered image in photoshop and follow his simple instructions from there....