Need help withre flections in huge file (hdri or photoshop?)

[mrstardust]

Hi,

 

haven´t done any archviz for quite a while and having some trouble putting my problem in the post title...

 

So, this is the task I´m confronted with at the moment:

 

I have to build a relatively simple scene for a client, showing only one view for a building with a glass fassade like this:

 

long link from google search

 

The output will be a 500cmx300cm print, so the resolution will be at least a couple of thousands pixel in length and width, depending on the dpi...

 

So far I haven´t found any hdris with a sufficiently high enough resolution for free on the net and the ones I found were still way too blurry.

Actually all of them were quite blurry even with the lo-res testrenders I did with them, so I´m not sure I did it right:

 

The second problem I got: I was also told to put some sun reflections on the building like in this image:

 

Another link

 

I used a glossy glass material on the windows, and tried to get those reflections from a vray sun, but I only got a similar effect, if I lowered the glossiness values below 1.0, but then of course I got blurry reflections of the sky, wich I didn´t want...

 

Since my HDRIs all came out blurry in the reflections, I also tried overriding the reflections with a texture in the environment slot (since I couldn´t find any panoramas or 360° textures of skys I just used screen as mapping method), but that just looked fake.

My current approach would be a combination of the two:

 

1. Render a pass with mirror like reflections, without any additional lights.

2. Render a pass where I lower the glossiness values and use a directional light to place some specular light on the glass.

3. Comp in photoshop.

 

Last but not least: The client wants a tree in the reflections, but I don´t want to increase my render times unnecessary, so how should Iput the tree in the reflections: Use a billboard at rendertime? Or just comp one in afterwards in photoshop?

 

I´m also not very good at compositing in photoshop, but I guess it would be easier to handle that kind of resolution in photoshop anyway, so I´d love to hear some input or links to tutorials how to tackle this project...

[Devin Johnston]

You need a very high resolution HDRI in order to not get blurry reflections, you probably won't find much for free that will work. Instead of doing that just map an image of a sky onto the glass of your building, that's a lot less complicated and will look about the same. If you want your glass to look like the one in the picture with the high secular reflection of the sun you'll probably need to fake that in Photoshop, it's the easiest way. As for your tree placing it in the scene as a billboard is the best option because it will pick up lighting as well as cast shadows and reflections onto your building.