Viewport black jagged lines

[Anonymous]

Hi dear community, I am having this kind of artifact in the perspective view, that looks like the display precision issue. (I tried to change the system unit, the viewport clipping, nothing works. Only changing from perspective to orthographic will work.)

Any ideas on how to make it behave like it's supposed to be? 😄

When you zoom in a little bit, it will get a little better, but the artifact is still there. Only when you zoom in to a close up, the display will then be correct.

Only when you switch from perspective to orthographic, the display will be perfect.

[RobH2]

It's possible you scale is off and your objects are really huge or really small. Also, you can get this if your objects are a really long way from the 0,0,0 origin. Check those things and I think it might clear up your issue. 

[BenBisares]

I agree with @RobH2. A quick way to work around this is to enable Viewport Clipping and just nudge the "Near clipping" slider up a few pixels. Should clear things up.

[Anonymous]

Thank you guys, actually, before I posted my question, I tried all these typical solutions, including the unit and viewport clipping. None of them worked.

Here attached my file. (It's actually my 5 yr old daughter's file.) Thank you so much.

[Anonymous]

I think I found out more reasons. The default grid is really small compared to the scene. But when I change the system unit (right) and display unit (left), the issue will not go away. In the system unit settings, by default, "respect system units in files" is enabled. I disabled it, then found out that all the numbers in my existing objects' dimensions are gigantic. But the problem still exists.

So now the problem becomes, how to change the original grid size in the viewport. I think that's the key.

[RobH2]

I see this and will have a look at it and get back to you. 

[RobH2 · Accepted solution]

If you are saying a 5-year old made this file, I'm impressed...really...  How cool is that? I would love to see what she's doing in 40-years...but I won't be alive...lol...

My son included, but a majority of the population has never known a world that did not have computers and cell phones. That's amazing. I had 8-track tape players in my car in High School...

Rambling aside, your file was set to mm and the ground plane is 143 feet. First of all, that's a lot of millimeters. It's good in Max to set a scale that makes sense. If you did a 5 acre plot, you'd set meters and not cm or mm. I changed the scale of your file to meters and moved it to 0,0,0 by attaching everything to a point helper. I forgot to see how far it was from the origin but I think it was pretty close. I think this issue was the scale setting. 

I've attached a file that I rescaled to meters and the ground plane is still 143.161 feet long. The screen issues are gone and it looks good, at least on my 4K monitors. Open it and let me know what you see. 

Edit: I see above in your screen shot that the scale you show is meters. However, when I open the file you uploaded, it comes in as mm. Odd, but that's what I get. 

[Anonymous]

Thanks RobH2! Yeah, my daughter got some help from me. Or you can say she used the voice command to control me to make this birthday party for her. 😄

I will check your file and see if I can repeat your process to fix it myself. 

Love to hear you "ramble". 😄 Thanks again!

[Anonymous]

Follow up, my takeaway is, the system unit and display unit have to BOTH make sense. And the setting "respect system unit in files" is actually very important! When I correct all of these, the size of each object then became ridiculous, showing me how far they are from the reasonable sizes. Once I scale them to reasonable sizes, everything looks good. I guess this has something to do with opening external files and somehow let the system adapt to the unit in the files.

[Anonymous]

Hi Rob, so now my problem is fixed, thanks to you, I want to further fix this issue.

Because I used scale to fix the unit issue, which messed up the xform, now each object shows ridiculous dimension but actually look quite normal. Is there any tool/script that can fix all the xform issues in the scene with ease?

Thanks again!

[RobH2]

I may not understand your problem but if you take the file I sent you and click on the green ground plane for instance, it's a believable size, 143 feet long, that's if all the things are kind of believable scale.

Don't mess with the scale and select everything then click 'Unlink Selection' and it will break the link to the XForm. As long as things display properly, does it really matter to you what the actual scale is? I mean, you aren't building this thing in real life are you? 

Otherwise, keep a copy of the original file I sent and make a copy. Play around with scaling, linking to a helper or point, etc., and you'll figure it out. I don't know how well you know Max, but a lot of it is playing around with one thing for a few hours till you get it. Then, you know that thing pretty well. After you do that a few 1000 times, you will be pretty good...lol.... 

[Anonymous]

Hi Rob, thanks again for your help.

You are right, I am not going to build this in real life. 😄 I am just being curious on how to solve some real issues. XForm has been bothering me for over 20 years now since Max 5. The issue that I ran into is just another small issue that I tried to solve for fun.

The reason why I ask about XForm is, if XForm is incorrect, the dimension reading in the measurement tool will be off too. For example, a pink box size is actually 20 meters in my scene, but when you open the modify panel, the length of the box actually shows 68000m. I know how xform works, but if I have a huge project and thousands of objects, it will take e a long time to correct them manually.

I tried to select all, reset xform, then convert into poly. But it will also destroy some modifiers. That's why I am searching for a better solution for the sake of curiosity.

[RobH2]

Sounds like you have some Max experience and have used it a while. I'm deep in a project now so my ability go dive in and diagnose is curtailed for a bit. Well, we solved the display choppiness, that was the main task. I'd take the file now and start playing with different ways to scale it and see what you can figure out. Some will work and some won't. Use a file copy you don't mind destroying. Yea, destroying the stack is not something good if you need those modifiers. 

I don't mean to dump you at this point but I'm on a deadline for a week or two. Just play around with attaching to point helpers or dummy objects, scaling and then breaking the links. I know that one reason to use an XForm is that it retains the parametric measurement parameters. If you just scale a 'box' for instance, I believe you lose those actual parameters. This will take some playing around. I'm betting your daughter can figure it out. 🙂

[Anonymous]

Thank you for your generous help. I learned a lot from you. Good luck with your project! I will share my discovery once I find some efficient ways to solve the xform issue. 😄

[RobH2]

I know this isn't possible if you get a file from someone else or the web, but the best first line of attack is to just make sure your scale is correct before you start modeling. And, make sure it's at the coordinate center. I know that sounds like an obvious thing but I can tell you, I've stared modeling with meters set for the units for jewelry and for mm set for units for mountains. I try to remember to set my scale to start with but sometimes forget and then have problems later.

Also, if you import things, you have to remember to immediately bring them to the center coordinates before just jumping in and modeling. Otherwise, you risk doing a lot of work way, way far away from 0, 0, 0, and causing problems. That isn't always an option if you need to keep that alignment so when you export back out it goes back to where it came from, but those are probably less common scenarios. 

I keep my 'maxstart.max' startup file set to centimeters. That seems to be a good balance should I forget to change. It also plays nice with a lot of other programs that use the metric system and if one needs meters, it's an easy 10x rescale if necessary. THen you can always set the display scale to read 'Decimal Inches' if that's more friendly for modeling while keeping the underlying units to a more universal metric setting.