scratches in perspective view

i'm using max 2009 and i got a problem in perspective view.

in picture 1, it's a space i've created, there is no problem at all in close zoom.

in picture 2, we can see a little scratches on the wall, but it's still ok. probably it's just normal for a thin wall in a very large area.

in picture 3, problem happens after i saved the file and open it again the next day, the whole scene is full of scratches. there is no affect on render output. but it's so painful to work it in pers view.

it's actually a model i've created in CAD and import it in max, whenever i import it again, it's ok (just like picture 1 and 2). however when i open it again a certain time later. it becomes crappy. is there any way i can fix this problem?

i don't have the max file in hand right now, probably i will upload it here later if necessary.

please help and thanks for reading.

Did you move your model to X0,Y0,Z0 in Autocad before Importing into Max? Studio Max doesn't like models that are far away from the origin.

yea i always do it from 0,0,0 in CAD, easier for my precise import tho. well i didn't know that max doesn't like anything far from home point.

i wanted to upload the cad file for your reference but it exceeds the size allowed in this forum.

You can send the file to me. The link in my signature will take you to my website where you can contact me via email.

Ok, I had a look at the files you sent and I have a solution for you.

1. Select your model

2. Right click and select "Object Properties"

3. In the Properties dialog, click on the "General" tab

4. Under "Display Properties", put a check in the "Backface Cull" box

5. Click Ok and your problem should be gone

I think what was happening is that some of your objects are very thin, so Max was actually viewing the faces as being almost overlapping. By enabling "Backface Cull", you are telling Max to ignore the backside of all poly faces, thus making them invisible and see-through from the backside.

thanks for the advice, it works.

i was having doubts on your answer that,

1) i understand why 20mm thick glass panel got this scratches because they are just way too thin to be displayed as 2 separate faces, but why my other walls with 100mm thick have the same problem.

2) why it looks quite ok while i just imported it in the max, and all the scratches come out the second day i open the same file.

3) i was thinking if there's anything to do with the light source, cos when i try to rotate the scene, the scratches seem to be interacting with the shadow/light.

so i did a simple test to save the max file in 4 different version.

i)the imported objects with backface cull and 1 light source

ii) the objects with backface cull without light source

iii) no backface cull with light source

iv) no backface cull no light source

and i found that there's nothing to do with having light source or not. the 100mm thick wall is relatively better than 20mm thick (less easier to have scratches), but they both got the problem when zooming out, as they are both considered 'thin' at a far distance.

but the problem is all solved when i turn on the backface cull. everything you saying is true. thanks for the advice again.

remark: when i first turn on backface cull, the scratches in the scene doesn't go away. now i know that i have to reopen the file in max to see the changes happen.

What? You doubted me?

LOL

I don't know why Max is being picky about your wall thickness, but I have seen this behavior in files imported from Autocad before. I don't think Max likes CAD files very much. But, simply enabling backface cull seems to solve the problem.

err...... not anymore