Sharp shadow line

[mcvltd]

Can anyone shed any light on why I'm getting a nasty sharp shadow line when the light is at this angle to the hull? I can adjust the light angle which eliminates the problem, but was wondering why this happened?

Rob.

[Mirko]

Looks like a smoothing problem in the mesh. Did you use boolean to create those round windows?
Try to analyse the mesh in these areas (try the "STL check" modifier). Maybe there are some unwelded points.

[mcvltd]

Mirko - mmm... could be. Mesh was created from a Rhino model and exported as an obj. Will take a close look at the mesh and see if there's any welding to be done.

[mcvltd]

Well.... I tried the stl check and it showed no seams in that area, but I welded the points just in case - problem was still there.

Re-smoothed with auto-smooth groups - problem was still there.

Tesselated the mesh - problem was still there.

Don't think it's a mesh problem.

[instinct]

Maybe a seam in a reflection, or surface texture ? Or a light with too small ranges ?

Thorsten

[dlparisi]

If you unheck "smooth surface shadows" and "Area Shadows" do you still get the problem lines?

[mcvltd]

Removed environment image - problem was still there.

Surface texture of water is all procedurals so nothing sharp to reflect there.

Light has no attenuation so ranges aren't active. The hotspot is greater than the boat and overshoot is turned on.

Unchecked smooth surface shadows and area shadows - problem was still there.


Keep those ideas coming!

[DaForce]

Try dropping your light bias.

Try 0.05

[jacksc02]

yeah, drop it to something nice n low like what daforce said

[mcvltd]

...here we go guys, nice and looowww - bias = 0.001

Just rendered the hull and water this time (for speeds sake).

Bloody line is still there!

[Candelero]

post your material setup, the cutoff value ?

P.S.:
IMO, this looks like geometry problem.


Best regards,
nikki Candelero

[mcvltd]

Nikki, cutoff value is left a default for all materials. I'm not too sure what the cutoff value does to be honest.

I'm not so sure it's a geom problem. Think it's got more to do with how the ray traced shadows react when they're traced over a surface that goes from concave to convex. I think also that the high incedence angle of the light has some part to play too.

Here's part of my max file... www.mcv3d.co.uk/doww/vray/shadowline.zip

And here's a render with a different light angle.....

[gilpo]

It still looks like a smoothing group issue to me. Are the polys to the left and right of the shadow line part of the same smoothing group?

[mcvltd]

All polys on the hull share the same smoothing group (1). Is this good or bad? (you'll have to excuse my ignorance, haven't been using max very long).

[DaForce]

Its actually the light.. and the way the ship is modelled it a shadow cause by the ship itself. If you move a user viewport into the alignment of the direct light you can see what i mean.
So its just a shadow line... totally normal.

Increase your Area shadow size up to 200,200,200 and you will see the line fuzz out as its actually a shadow created by the over hang of the boat and the reason its so sharp and looks like a problem is because due to the scale of your scene you need to ramp up the area shadow size for it to have an affect. If you move the light a little and increase the size of the area shadow you will notice the line has moved and its now softer.
So what I am saying is there is no problem what so ever.. you are just seeing a shadow

P.S. that model aint so good either.. lots of double edges..etc..etc.. but hey.. if it renders fine then cool