Known shadow bug?

[Rick Thompson]

I am going to post several renderings. Notice the shadows from the house and the car. Sometimes you see the shadow, somethings not. If I move the car half off the drive, I get a shadow, move it on.. it might go away (along with the house shadows), but if I am lucky, it shows long enough to generate a sketch rendering. That seems like a bug to me, so I am curious if this is known or not.

thanks

1st is shadow not generated

[Rick Thompson]

Car half on, it generates a shadow

[Rick Thompson]

I got lucky here, and get shadows with the car on the drive, but this more often than not eliminates the shadows from the car and sometimes the house.

This can kind of make you nutty.

[Anonymous]

Rick, I wish I could answer your question but instead have a question for you. Are the shakes on the gable and the clapboards on the house, part of the AC library or from somewhere else.

Thanks,
Doug

[Rick Thompson]

It's just a custom fill I made with lines. I could probably place it on an empty pln and email it to you if you like. If so send me you email address. However, it was easy to make.

[Dwight]

Sure seems strange - which car?

[Rick Thompson]

A Mercedes!

ArchiCar 1 from Alfavilla ArchiCars. It's even weirder than i described. I first made the brick sidewalk, then the drive. I put the car on both and it case a shadow on the brick, but not the drive (half the car made shadows, the other half did not). I thought it must be the slab settings, so I changed everything I could for the drive.. no change, and then injected the same settings from the brick to the drive... None of that changed anything. I deleted the drive, made the sidewalk bigger.. etc. The only thing that seems to influence it is moving the car partly off the drive, then I get a shadow. They are set the same height. It weird that the shadow on the drive from the house becomes on and off, with the car.. or so it seems.

Notice in the top rendering, the house is casting a shadow on the car, but not the drive.

[Dwight]

I don't have much occasion to use the analytical shadow casting render method, but last week i was trying to demonstrate the copy-shadows-into-the-plan-view trick and had some inconsistency in shadows cast. The guy I was answering could only get parts of his model to cast shadows as well, so I was verifying the matter.

And so it goes. While I can see that Archicad might reject the shadows from a complex object like a car, my simple boxes were also affected.

[Ralph Wessel]

Rick wrote:
I am going to post several renderings. Notice the shadows from the house and the car. Sometimes you see the shadow, somethings not. [...] That seems like a bug to me, so I am curious if this is known or not.

I see this too sometimes, but with walls or roofs in elevations with cast shadows. Out of the blue one roof or wall will not cast a shadow, which often stands out really badly. It's very rare thankfully, but I don't have a definite method for fixing it. Sometimes just looking at the element settings does the trick. I suspect it's a precision problem deep in the bowels of ArchiCAD's polygon-clipping procedures, i.e. a bug, as you surmised.