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Posts: 89
Reply with quote  #1 

My work requires me to often create visuals of basement kitchens and other such rooms that often have no natural light sources, so I then start randomly chucking in either light fittings from the Podium Browser and hope for the best, or more commonly I make some extremely basic LEM rectangles and keep them out of direct sight in the field of view. However, I'm pretty clueless and end up wasting a lot of time adjusting material's LEM properties up and down, then I often lose patience and settle for a poor result. Please could someone point me in the direction of some basic guidelines for illuminating such scenes.

[Moderator note: Moved from the Tips, tricks & tutorials thread, because it's neither of those things. That thread is for posting those things, not requesting them...]

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Posts: 10,921
Reply with quote  #2 
Without some images to illustrate the results you are getting, it's difficult to offer meaningful help.

In these cases, probably the best solution is to rely on your light fittings to illuminate the scene. The fittings themselves should be sufficient.

You have a number of things that can help.

First of all you have the presets. There are brighter presets for interiors which boost the lighting levels.

There are the HDR presets (make sure you use the .hdr output type) that capture a higher dynamic range, so it's easier to post-process

You have the Podium Image Editor to adjust the brightness. You will get the best results with hdr format images.

If you are expecting Podium to produce images which look like what you expect to see in reality, in many ways it's unrealistic.

What we 'see' is not real. Our brains interpret the visual data and apply kind of a realtime automatic tonemapping to the data. If you have ever photographed an interior with a camera and found the image way darker that it appears, this is why. The camera is capturing the actual lighting level, but your brain is making what is actually there look a lot brighter.

In this respect we are expecting the render engine to simlulate what our brains interpret, not what is actually real!

In this context, using an image editor doesn't seem unreasonable at all.

Fill lighting is a fix you can use when there is a problem with the other solutions, or where you might want a scene which is artificially bright.

It is good for simulating the light of a camera flash for example, or indirect light being bounced from an adjacent space outside the view.

Given these criteria, it seems to be entirely logical to make the LEM large, white and low power. You should always be able to identify the shadows from the primary light source(s).

Lots of people post images where they have added fill lighting and the shadows are all wrong because they are from light sources that are not visible, or the indirect lighting is all washed out. This makes renders look flat and unrealistic, or 'uncanny valley'.

Post some renders and we'll see what we can do to improve them [smile]


That which does not kill us makes us stronger
-Friedrich Nietzsche


Posts: 1,797
Reply with quote  #3 
Thanks for the post and the question.  This situation is a bit tricky because sun light  is very effective in illuminate an interior.  But what are you going to do if you are doing a mall design or rooms with no windows, etc?

1. Here is a tutorial on LEM fill lighting.  As Big Stick pointed out it may not seem as realistic as a sun light.  But this might get you started with experimenting with fill lighting.  In this tutorial hidden LEM is being used as well as some recessed lights.

2. I have posted a panorama of wine cellar (no natural light here) done by Nat just to give you an idea that artificial lighting can be effective.  All the lighting is coming from light fixtures and possibly behind the scenes LEMs.

3. This may be unrelated to what you are trying to do but this is a good Tutorial by Justin on how to acheive studio lighting.  This one features ProWalker but can be done entirely in SU Podium.

4. Light fixtures - possibly easiest mothod is to have a grid of recessed lights in the ceiling to get a good balance of artificial lighting.

Here is an image of a classroom (done by Nick) that has no artificial lights.  There is no tutorial that comes with this but using Podium Browser' recessed lights can make this job fairly easy.    There are a lot of recessed lights in PB and you can control the light power.  Accentuate the ceiling lights with some floor lamps might be effective.

The problem almost always is having to use a _high _QMC preset because using only artificial lights with a lower (but faster) quality preset like _default, usually produces some blotching.

In this example the strip lights are LEM and the recessed lights are point lights.
3D CFE2 Final.png 

5. Controversial method but effective -   If you are not doing panoramas but still images, an often used technique is to hide or remove the wall behind the camera to expose sunlight.  Turn shadows on and manipulate the sun/ shadow using Solar north so sunlight is illuminating the interior...without actually seeing the opening behind the camera.  It's controversial because your client may not want sunlight in the interior space..

But putting a large LEM behind the camera is another method.

6. .hdr - rendering to the .hdr format and then adding tone mapping in PIE or PS gives you more flexibility.  You can do this with Podium Image Editor.  Changing the light levels will help as well if the room is a bit too dark.

I hope this helps a bit. I do think an enclosed interior tutorial would be a good one for us to write.

If you can send us some image examples or even upload the model at (only support people will see the model), we could give you some tips.


Posts: 89
Reply with quote  #4 
There are some good pointers amongst those posts, thank you. I'll have a go at them before I start taking up any more of your time with uploads etc. From day one I have always used .png format as I mistakenly thought that gave the best results - maybe it was because it allowed transparency for when I do exterior designs that kept me with that format. I know nothing about .hdr so I will make that change immediately.

Posts: 1,797
Reply with quote  #5 
I think using .png is fine. 
Read about .hdr here and it's advantages and disadvantages.

Here's a office rendering.  I closed off the Windows so no sunlight would enter the space.
I did have to use interior_bright_high though and that took a substantially longer time than using a interior_bright_default.

large-office-room-no-windows.png  The above image is .hdr and as you can see dark.  But you can adjust the light level in PIE or PS.
What happens with .hdr, even though the there should be a lot more light range, I think the file is compressed for the screen so you have to add back in tone mapping.
There is a nice feature in PIE coming in V2.6 which is automatic adaptive linear which automatically adds back in tone mapping for .hdr files.  Both files were rendered as .hdr then after adding tone mapping saved as .png.

large-office-room-no-windows-adaptive-linear.png  I have a bit of glare with the two lights on the back wall but I could correct that by lowering their light power values.

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