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PostPosted: Tue Jan 31, 2012 5:37 pm 

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Image

I am trying to achieve a similar lighting effect as in the above photograph. I'm having trouble getting a dusky sky with a bright building (exterior & interior). Does anyone have any general tips on how create this in MR?

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PostPosted: Tue Jan 31, 2012 5:53 pm 

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To me the sky looks entirely photoshopped based on the uniform gradient and the white 'halo' around the building.

For lighting I'd say an HDR with a warm evening glow perhaps? The lighting is very uniform so I'd think that would work well.

And maybe a photographer could chime in but the foreground lighting looks a little odd to me (not necessarily in a bad way). It's almost as if there's a flash coming from the camera area or something.

-Brodie


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PostPosted: Tue Jan 31, 2012 6:03 pm 
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I have to agree that the sky is added in post, they usually are replaced in architectual shots like this one. This example is pretty poorly done to be honest.
But what i guess based on the lighting in the front of the building is that it 'could' be shot with existing lighting but just a long exposure to make it bright enough. Or they could have used a big two meter silver flash reflector to illuminate the building but i have some doubts about that.

/ Magnus

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PostPosted: Tue Jan 31, 2012 6:13 pm 

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Yeah, I've been thinking I'll need to photoshop the sky, can't seem to get it quite right with Maxwell skies. My main problem is lighting my model. right now I have some decorative fixtures lighting the building, but also some hidden giant blocks of emitters to give an ambient light. Do I just need to pack the building with lights?

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PostPosted: Tue Jan 31, 2012 6:19 pm 

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For the most part, the closer your lighting is to reality, the closer your result will be to reality. If you just fill the building with large invisible emitters you'll have issues with regards to that. Your starting point, then, should be to have place a bunch of lights with reasonable wattages in reasonable locations about the building close to where they'd be in reality.

-Brodie


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PostPosted: Tue Jan 31, 2012 6:25 pm 

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brodie_geers wrote:
For the most part, the closer your lighting is to reality, the closer your result will be to reality.


I wish I could believe this, but I have not experienced my desired result with lighting as it would be in reality. It's quite probable this is my error, however. Are there any tutorials you would recommend fro achieving accurate lighting? This is my biggest MR weakness.

Here is my first shot at the image:

Image

I have trouble with the actual sources being super bright, yet not creating much ambient light on nearby surfaces. The interior continues to be dark.

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PostPosted: Tue Jan 31, 2012 6:39 pm 
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That sounds like a scale issue -- make sure you are working at 1:1 real world scale for realistic lighting effects.

Also the geometry matters -- if the emitters are grouped as 1 object they could be considered 1 piece of geometry and the total surface area would need to be considered for the emitter material power. Using Multilight can help you quickly test for those types of issues.

Best,
Jason.

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PostPosted: Tue Jan 31, 2012 6:46 pm 

Joined: Thu Nov 13, 2008 2:52 am
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Maxwell doesn't fake any lighting so if it seems like the light is bright but isn't creating ambient light there's a physical issue. Here are some possibilities.

1. scene scale: if your living room is scaled to 120'x120' instead of 12'x12' the light look like it's falling off too quickly.

2. gamma: make sure your gamma is between 1.8 and 2.2 depending on your computer. I think 2.2 is pretty much default now.

3. light power: a small emitter at 100w is good but if you've got a large planer emitter at 100w it'll be very dim. make sure your emitters have a realistic power rating

4. camera exposure value: in tandem with realistic lighting make sure your camera settings are realistic. check this chart http://en.wikipedia.org/wiki/Exposure_value

-brodie


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PostPosted: Tue Jan 31, 2012 7:05 pm 

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I might post this to the Mr for SU board, but I'll try here first: how do you adjust the temperature of emitters using the SU plugin? All I can find is color by RGB. Trying to create realistic emitters but not sure how RGB matches up with Kelvin.

I am at real world scale, gamma at 2.2 (default). Have adjusted my emitters based on the size of the object. F-stop 5.6, ISO @ 800.

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PostPosted: Tue Jan 31, 2012 7:10 pm 
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That has been added to the new 2.6.10 plugin -- so you should see that when setting up an emitter material once you have the new version installed.

What is the EV? and the Focal Length of the camera?

Best,
Jason.

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PostPosted: Tue Jan 31, 2012 9:07 pm 

Joined: Wed Nov 19, 2008 4:06 pm
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Sweet, I didn't realize there was a plugin update too. I like it!

EV is 14, can't figure out how to find the focal length. SU will only show me field of view right now (45 deg) when I use the Zoom tool.

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PostPosted: Tue Jan 31, 2012 9:14 pm 
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EV of 14 is way too high -- you will likely want to set that to at least 9-10 for the effect you want... make sure you read all the way through this link: http://en.wikipedia.org/wiki/Exposure_value particularly the "Tabulated exposure values" table.

You will also want an alpha channel render for post purposes.

The field of view can accept input in either deg or mm -- setting it in mm is what you want to control the focal length since it will make more sense photographically.

Best,
Jason.

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Last edited by Half Life on Tue Jan 31, 2012 9:18 pm, edited 1 time in total.

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PostPosted: Tue Jan 31, 2012 9:16 pm 

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I figured if I typed in something in (mm) it would change it, but I can't figure out how to display what my current FL is. Do you know how to do that?

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PostPosted: Tue Jan 31, 2012 9:31 pm 
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Try dropping this into the Ruby Console
Code:
Sketchup.send_action(10624)

Then you can just use a calculator like this: http://kmp.bdimitrov.de/technology/fov.html to convert the values.

Best,
Jason.

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PostPosted: Tue Jan 31, 2012 9:34 pm 

Joined: Thu Nov 13, 2008 2:52 am
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Once you edit your focal length to be something like 35mm in SU, from then on it should display in mm. Are you saying that isn't the case?

-Brodie


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