Z Fighting In Renders?

[keithhe]

Are there any new tricks for reducing or eliminating Z-fighting in renders?

 

The only two I'm aware of, and usually work, are to "thicken" the material in the DBX and setting camera defaults/ Scene Clipping/Clip Surfaces Within to 300-400" which usually works. In fact had not seen it for a while and I thought perhaps X6 fixed it, but nope, it's still there.  

 

Only ever really see it on roofing and lesser degree on siding and just wondering if there are any other tricks to reduce?

 

Thanks,

[Larry_Sweeney]

Try making your clipping distance farther away. I find that sometimes I have to go quite a distance. I'm not sure what goes on if you make the distance to far, but just play with the numbers and see if that is the problem.

[keithhe]

Thanks Larry,

 

I went up to 400" with no appreciable difference. Checked my card and it's up to date. Finally I reduced my admittedly large terrain and that calmed things down a lot. Increase siding size and forgot how to do the same for shingles? I think I found it via the rainbow tool, but I thought there was another way, similar to the wall definitions and layers.

[glennw]

If the model was a long way from the origin, it used to cause z fighting problems.

I have a vague idea that they fixed that, but worth a check anyway.

[keithhe]

Thanks Glenn,

I checked and have center at middle between two plats of most concern. I think primarily I had too large a terrain. Scaled that back, plus camera settings as well as material changes and it's gone, for now. Glenn, is the only way to change shingle thickness via the rainbow tool? Wall related materials are easy enough, but shingles I'm not sure I have right. I also read someone saying to "paint" the OSB sheathing shingle, but no idea how you would do that. Is there a way to "hide" shingles so just OSB shows to allow that?

[mcrump]

My fix is to simply change the underlying material to be the same as the surface material.  As an example, if I have Z-fighting on a roof I change the material for the plywood to the same material as the shingles.  Works like a charm.

[keithhe]

Mike,

 

So you change the OSB (chief default) to shingles? Where do you make that change?

[Kbird1]

you change change the Sheathing thickness in the Build Roof DBX> Options>Roof Layer section

 

and the materials on the Materials Tab

 

[DavidJPotter]

For roofs, I make the sheathing the same material as the roof surface to termanatedly hangle Z fighting relative to roofs, that change is made in the roof plane specification dialog - Materials Tab per roof plane.

 

DJP

[dshall]

For roofs, I make the sheathing the same material as the roof surface to termanatedly hangle Z fighting relative to roofs, that change is made in the roof plane specification dialog - Materials Tab per roof plane.

 

DJP

This is crazy stuff. I never see z fighting on the roofs. I wonder why.

DJP trick will work unless you want to see starter boards at eaves, then you must change osb to decking.

[VHampton]

As a rule of thumb I always make the roof thickness 1". We use wood shingles on most every project and at the end of the day not only does this make 2d layout views read correctly, it solves the all too common distortion effect from Z fighting.

 

Also...the terrain perimter should ideally be spread pretty uniformly around the model. If you've got too much real estate towards one end of the house it can create a lopsided effect which sometimes results in the Z fighting.

 

In addition to the roofing it can help to thicken the siding as well. Often I will elimnate the plywood layer and make the exterior siding 1" thick just like the roof. If you don't want to kill off your plywood layer, just change it's material property to match up with the siding. Two layers will stop the bleed through effect. (...just like David suggested)

 

Between the roofing and siding changes, this should make your model bullet proof in terms of avoiding distortion.

[keithhe]

Thanks Dave. That helps refresh my admittedly lousy memory.

Val, I agree, the siding is something I had started doing long time ago, but the terrain one is what screwed me on this one, primarily. This is way more terrain than I had ever done before that contains the terrain contour data for the neighborhood out several houses either side and across the street, lake, which I went out to the "deep end" so to speak, and immediate neighbor houses, boathouses as symbols. The thing that immediately tamed it was to reduce the lake back toward shore.

The camera clipping trick also works well, until you try to use it in a close in situation where you need to change it back or a lot in front of you will be gone

Scott, I know you are working a subdivision thing, try going stupid large on the terrain perimeter and see what you get, as an experiment. No video required.

[dshall]

.....

Scott, I know you are working a subdivision thing, try going stupid large on the terrain perimeter and see what you get, as an experiment. No video required.

Here it is.....  this site should be about the size of what it will be in the end when all houses are placed.  The z fighting I see is from the rafters and not from OSB.  I ignore this....  it never shows in layout. 

 

And when I am reviewing overhead views I always use renders and not vectors so that is never a problem.

 

As a side note,  I do not understand why many people use vectors for reviewing overhead views.  Renders always look better and in the past they were always quicker than vectors.

 

As another side note,  this site is made up of 11 existing homes that we are going to remodel and there are 7 other homes that have been or are being built now.   

The site is anything but flat.  Periodically as I work on the terrain,  I will do some videos that you can watch if interested that will show the typical anomalies that show up.......  you know......  the stuff you can't explain even though you think you have the terrain built correctly.

[keithhe]

Thanks Scott, so it can show up with really large terrain, and I think perhaps the more terrain contours the more likely, but can't prove that. Add loading it up with a lot of "stuff" and it can happen to some degree. I was even seeing it on the house symbols imported which struck as me as weird, and would have to change them in their plan, then make new symbol, or find another solution. In my case, primarily the terrain was the issue. Who knew you couldn't model a 36 mile long lake in a single plan?? Kidding, I was only doing a section of it out from the shore.

 

Knowing how to battle it is the key, where it might matter. If you see it in a render it will be there in the ray trace, for example. I suspect everyone has seen it at one point or another and hopefully this thread can help people that search it out on ways to reduce or even eliminate it.

 

Scott, really interested in your subdivision project and will follow your progress on that.