Landscape Collision Stuckness via PhysX 3.3 Makes Landscapes Unusable in Beta5

Dear Friends at Epic,

I am having a real problem with landscapes in beta5,

in beta4, my character could free roam over the terrain, limited only by the step size of the character, and everything felt somooth and beautiful, quite joyous actually. not quite as good as a girl but as good as a landscape can be.

Collision Stuckness

as you can see above, the logs actually confirm my character is literally getting stuck on the landscape

this never happened to me in beta4, or ue3 landscapes which I used extensively!

now in beta5, my character will occasionally get stuck at often random places, but places with some kind of slope change

and the most annoying part about it is that after they get stuck they can either only move in 1 or 2 directions, or not at all, and I have to make them jump to be able to move at all again

When this stuckness happens, the character very very rapidly loses all velocity, which is very unrealistic and really interrputs any flow along the landscape

this completely halts the flow of my gameplay roaming over the rolling hills and mountains of my landscape!

I find this extremely irritating especially because it was so slick and smooth in beta4

#Collision Mip

I tried changing the collision mip level on the landscape, and this helpd a bit, but I can only raise it so high before it is too blocky and inaccurate.

A collision mip level of 1 produced the best results, closest to beta4

but still, character does get stuck

and mip level of 1 is still noticeablly inaccurate and on steep slopes my character will sometimes fall through the landscape which is REALLY bad for gameplay :slight_smile:


Please address this, it is very annoying to me because it stops all gameplay and stops a fast paced action game where you are being chased and have to have quick reflex but


hold on a minute

got stuck on the terrain

*monster eats player *

This means that survival is no longer in the player’s hands, it is a matter of the whims of the landscape collision system


please fix this

and let me know what else I can do


again in beta4, the only limiting factor was the character step size and this NEVER used to happen

#Want my landscape?

I can migrate my landscape for you if you want to test it,

it was unchanged from beta4 to beta5

all that changed was whatever happened to landscapes and collision internally from beta4 to beta5



#Attempted Solution 1

I tried making some changes to the heightmap itself in the areas of stuckness,

and then did a complete level rebuild including lighting

but this did not cause an improvement of any kind

#Attemped Solution 2

I tried doubling the step size of my character

this lead to absolutely no change not even a lessening of the stuckness behavior

this leads me to believe that the character capsule and the landscape are actually having collision issues that they did not have in beta4

#Attempted Solution 3

I tried checking off on the character collision capsule

  • always create physics

  • trace complex when moving

  • notify rigid body collisons

this caused no improvement, and actually made walking more clunky feeling

Hi, we upgraded to PhysX 3.3 and transitioned to using the heightmap collision code that treats heightfields the same as triangle meshes.

If you could send me a level or export a landscape heightmap that has these problems, I’ll take a look and ask Nvidia’s for help.

Thanks Jack!

This is a really big problem for me, it is literally stopping my gameplay with my landscape

I have uploaded these files to dropbox:


you can expect errors at launch due to none of the materials being present or some of the classes :slight_smile:




#One More Thing - Steep Slope Collision Inaccurate

If you try moving along the steeper slopes in my map, with a step size of about 67, you will notice that the collision does not match the slope very well!

In beta4 it was perfect

#Foot Placement + Steep Slopes Not Good in Beta5

I notice now that along steep slopes my character floats above the surface of the landscape quite a bit

to the point that my foot placement system no longer activates

because it is tracing complex collision with the landscape

I do have landscape Mip set to 0

I hope you can address this as well!

Thanks Jack!



#Repro with .Raw

I have indeed reproduced the error just importing my .raw from dropbox into the starter ue4 map and using size to import

I had to run around for about 20 seconds but then the log errors showed up as well as my character actually getting stuck form gameplay perspective

Dear Jack,

I have also tested the map I am sending you, where I removed a lot of stuff, all you have to do is roam around for a bit, sometimes near areas of steeper slopes, sometimes not, and if you are watching log you will see this eventually (took me about 12 seconds)

Hi, please paste the dropbox links. You just talk about the dropbox files but no-where do you provide a dropbox link…

I see, you mean the FTP dropbox, not the Dropbox service… I’ll see what I can do :slight_smile:

Did you get the files okay?

Let me know anything else I can do!

this is a huuuge issue for me

it is making my landscape basically unusable

Let me know what else I can do any time!


Rama drop box (we’re not allowed to host files externally)

you can expect errors at launch due to none of the materials being present or some of the classes :slight_smile:




Can you please stop editing your questions? I get an email notification each time you do so. It’s extremely confusing. I understand this is an important issue but spamming isn’t going to help it get fixed any faster.

I did not yet get your files because I don’t have a login to the FTP site, but I’ve asked for access and I’ll take a look at your content when I get it.

Thanks. With our character and your map, I can replicate falling though the landscape (rather than getting stuck) in the PhysX 3.3-based code. The same level doesn’t have the problem in the PhysX 3.2 code.

I tried disabling a feature that makes landscapes behave like triangle meshes but it didn’t fix it.

I need to discuss this with Nvidia, as it seems the bug is inside PhysX.

  • Jack

Thanks for the update Jack!

I look forward to more info from you any time!



I am absolutely not trying to bug you Jack,

but is there any update on this?

It is quite a concerning issue to me :slight_smile:

Just knowing of any progress being made will help me feel better :slight_smile:


Hi Rama,

We haven’t resolved this issue yet. We are still working on a reliable test case that can replicate the issue in the PhysX debugger.

The issue is tracked in our bug database as TTP#318613, and I’ve made sure it’s marked as a blocker so it will be fixed for the next Rocket beta.


Dear Jack,

The problem got reduced somehow in Beta6, my characters no longer get randomly stuck on the landsacape, using exactly the same landscape and map assets as beta5.

In fact this was one of the first things I loved about Beta6!

So something changed :slight_smile:

The remaining issue is that my characters do periodically fall through the map at partially random places, a behavior I did not see in beta5.

So there’s definitely been an improvement.

But I very much appreciate the “blocker”

#because landscapes are so awesome,

and so important for my game :slight_smile:

#Thanks Jack!


Hi Rama,

Thank you for your feedback. If you have not already, please create a new post about the new collision problem that you have encountered and I will be happy to further investigate.



I have done as you requested and I have really good news for Jack!

I think the new Beta6 landscape collision issues are NOT PhysX 3.3 related

I’ll close this thread and we’ll continue here:
https:/ /


#This Issue Has Been Totally Fixed As of Engine Version 4.3 !

I have wonderful news for you all!

Jack Porter has fixed the Landscape Collision Issue, with help from Zak Middleton!

Jack Porter deserves many flowers and butterflies sent in his general direction!

And, best of all,

This fix is live as of 4.3!

#Solution Thread