For shadows with perspective is it possible to use a path line with three points to calculate the blur length at the end of a shadow to make it look blurry further back and gradually get solid and more realistic looking? This would allow you to have a custom blur for any shadow. The current Perspective shadow blurs the entire outside or radius of the shadow and doesn't look very real. Or am i missing a setting within the filter to fix that?

I don't know of a way to do it as you describe, but what you seem to be requiring appears to be what the focus blur plug-in does.

You would have to create the Depth-Map manually, but then I suspect that the amount of blur is subjective anyway.

And apparently you don't need to be told where to find a copy of the plug-in

Kevin

Still looking for a technique for realistic shadows... Plain blur doesn't work because is expands the shadow, while the shadow get gradually thinner than the object that casts it.

Now that's cool Graechan. Link to Script-fu?

Now that is some shadow Graechan, I don't know how you did it but I would sure like to have it.

This is what I would do:


Which is a perspective shadow, with a focus blur using a black to white gradient as a depth map to get the "deeper" areas increasingly blurred, then a layer mask using the same gradient to fade the shadow.

.xcf attached

Kevin

(actually what I would really do is use POV-Ray to render it properly )

Is it just me, or in Graechan's result does it not make the letter 'P' seem closer to the viewer than the other letters?

Fluffybunny you are correct.
Thank you Kevin and Graechan that is almost perfect. Just needs more sharpness at the front of the shadow i think.

I was checking out the follow path plugin that was recently added to the registry.
http://registry.gimp.org/node/28647
I wonder if a blur option could be added to this filter as a option to gradually blur a perspective shadow? I asked the author to look into it.

guess I just got n'jd. lol. I was looking for my post and wasn't there, Yes Fluffy I also agree that it looks closer but maybe it is because the tail on the p goes below the bottom of the other letters. Tjhe script is really looking good though.

Here's what I get using POV-Ray

With a single point light source:


With an area light (14x14 point lights over a 2x2 area):

Some odd artefacts, but you get the idea.

Kevin

Yep. The closer the shadow is to the object casting it the sharper it should be.

I think that you can only fake because you need hight object distant for Light and angular of light for make real. The best would take render Model scene and work with photo as base.

Yes, the second one looks much more realistic. good job Kevin and Graechan for working out the kinks.

Graechan it seems to be in the menus as "<Image>/Filters/Light and Shadow/Perspective Advanced"

My settings

My results


Now i just need the lighting within the shadow.
I will play around with it some more.

Here is the results after using your Perspective-Advanced script (same values).
Then i selected the bottle layer and ran Shadows&Highlights script on the bottle then using transform to correct the angle over the Perspective-Advanced shadow layer and voila. Oh i did have to create a new layer with a white shadow under all the other shadows.