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Shadows blurry

Posted: Mon Apr 30, 2012 11:20 pm
by white-light-filter
When I go to walk though, the shadows (regardless of which lighting mode I use) are blurry and imprecise... to the point where you can barely tell they are shadows and not just ambient occlusion.

I have read the manual and search the forum but no luck.

What am I doing wrong?

Re: Shadows blurry

Posted: Tue May 01, 2012 8:18 am
by AdamB

LightUp works by calculating lighting and shadows on a regular grid over the faces of your model. The tighter this grid, the more fidelity you get.
Think of it as a bit like looking at an image of 10 by 10 pixels which shows very little detail compared to the same subject at 1000 by 1000 pixels.

So this lighting grid is controlled by the LightUp Preference "Resolution" which can either be given as a multiplier (default is "4x") - which is handy to get going quickly - want twice as much fidelity? Simply double the multiplier to "8x".

The image below shows little green-red ticks showing the lighting grid:
SketchUpScreenSnapz003.png (424.7 KiB) Viewed 2777 times
Resolution Multipliers are fine, but if you know the scale of your model, you'll probably want to specify an absolute distance between grid points, to have close control over quality vs time to light. So for a single room / house you may get rough drafts with "25cm" Resolution (meaning: Light my model at 25cm intervals which may give shadows that are a little blurred), but for final output raise it to "5cm" to capture more lighting detail.

So here is a soccer stadium (onto which I've added a white grid for reference) lit at increasing Resolution. NB you can use any valid SketchUp units: Imperial, Metric etc

Stadium(no scene)_2012-05-01_0907.jpg
Stadium(no scene)_2012-05-01_0907.jpg (60.58 KiB) Viewed 2777 times
Stadium(no scene)_2012-05-01_0909.jpg
Stadium(no scene)_2012-05-01_0909.jpg (60.52 KiB) Viewed 2777 times
Stadium(no scene)_2012-05-01_0910.jpg
Stadium(no scene)_2012-05-01_0910.jpg (60.5 KiB) Viewed 2777 times
The key point, is LightUp gives you full control over this - but always gives a fully anti-aliased image of the geometry.

Finally, sometimes you choose a Resolution for the model but may have extraneous geometry that doesn't need detailed lighting - but does need to be there. For example a large ground plane that really doesn't need lighting at 25cm intervals.

LightUp also has controls for this by using the QueryTool and Alt/Apple clicking on a material to show the Material Dialog:
SketchUpScreenSnapz004.png (28.39 KiB) Viewed 2777 times
You can check "Low density" to quarter the resolution used for lighting - just for faces using this Material, or check "High density" to bump up the resolution just for faces using this Material.

And finally, if you have faces which don't need lighting at all because they are "self illuminating" - for example a Sky billboard, or a GoogleMaps ground plane you've imported, then checking "Always fully lit" tells LightUp it can entirely skip lighting these faces and helps speed up lighting times.