This video will show you how to use the motion vector ROP.  Then I will give a brief overview of the material setup in UE4. And then I'll go into some of the details regarding how we calculate a useful vector in texture space.

[UPDATE 10 May 2019] - The ROP now has a raw multiplier value that can be used with the material function code at the bottom of the ROP. Just copy and paste the code into a material function, and input the multiplier as a scalar input.

You can download the latest motion vector ROP from the development branch of our Game Development Toolset on GitHub.

For more info about motion vectors and creating a UE4 material check out Klemen Lozar's awesome tutorial - Frame Blending with Motion Vectors

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• gaoshang1244 6 years, 7 months ago  |

NICE tur! How can do in houdini 15?

• Landerb 6 years, 4 months ago  |

Hi mike, I followed this tutorial exactly and all i am getting is the entire frame of each image running up and to the left with no distortion. Any suggestions?

• mikelyndon-sesi 6 years, 4 months ago  |

Does the motion vector texture look correct?
Have you turned on double apply motion vectors in the material instance?
Does your number of Columns and Rows value in the material instance match your texture?

• hdl35301 6 years, 2 months ago  |

Thank you for a wonderful tool.
I have a question.
If I turn on double apply motion vectors in Material,
Emission and Alfa flip correctly, and the motion vector continues to flip to the upper left.
If I turn off Double Apply Motion Vectors in Instance Material,
The Motion Vector flips correctly, Emission and Alfa continue to flip to the upper left.
How can I flip Emission and Alfa and motion vector all in the same way?

• mikelyndon-sesi 6 years, 2 months ago  |

Can you check the FlipBook_MotionVectors material function to make sure that the ConstantBiasScale in the Motion Vector Setup section has Bias = -0.5 and Scale = 2.0

• hdl35301 6 years, 2 months ago  |

I could solve it as I had you taught me.
I appreciate you very much.
Please keep making great tools in the future.

• Michelleshow 5 years, 12 months ago  |

hi , there's an error when I click Render Atlas and I don't know what I can do to fix. I use Houdini 16.5 . I am new to Houdini . Is there any tip?

• BlackRiverStu 5 years, 9 months ago  |

Hey, I`m facing what I believe to be an error on Houdini 16. When I render the atlas, the result frames are all stretched, with a different resolution from what it's said on houdinis interface. For example, on an 8x8 atlas, it says the frames will have the size of 128x128, but its comming as 100x720 for some reason.

I have tried an animation of 150 frames by using intervals of 15 frames, with no success, and tries picking up only 64 frames, with no frame intervals, and got the same error. The camera is orthographic and I`m using the commercial version of houdini.

Does anyone have a clue?

• dmarks 5 years, 9 months ago  |

Mike!

This looks excellent and is exactly what I need. I am having trouble getting the network into Houdini. I've tried both install methods outlined in GitHub, and no matter what I do I cannot get Motion Vector ROP to come up on my node view.

It is important to note that I'm currently using an Apprentice License, so that I can test these things prior to asking my studio to pull the trigger on a Houdini license. Maybe this is the issue?

Thanks!
Don

• dmarks 5 years, 9 months ago  |

Nevermind.... got it working. Thanks anyways. Great tutorial. Thanks for putting this stuff together!

• mellacita 5 years, 5 months ago  |

For some reason, I'm getting an all-black render. Have stuff loaded in the Export Node and the right camera in the Camera field, but won't render the motion vector at all. I also get an error saying "Error: rendering child" for the atlas.

What do you think?

• mellacita 5 years, 5 months ago  |

Figured one bit out--was using a non-commercial file and was exceeding the maximum resolution for the atlas. But not sure why the sequence frames are still black.

• jbaki 5 years, 2 months ago  |

I am trying to use this and get a bright yellow outline around my explosion.
There is also an alpha.
Are the lights in your scene above important?
Even with some photoshop to a no blue channel background the image looks nothing like Klemen Lozar's results.

• ViktorMartynov 5 years, 2 months ago  |

I could not repeat Klemen Lozar's material. It gives an error in "SubUV_Funktion". Share a link to the finished material or show how to do it.
Thanks!

• hflong240 4 years, 12 months ago  |

Can I create MotionVector from cloudfx ?

• mikelyndon-sesi 4 years, 12 months ago  |

I don't think so. The motion vectors ROP requires a velocity field and I don't thin the cloud sops generate those fields.

• allansimonsen 4 years, 10 months ago  |

Setting the Playbar to 1..100 (and indeed setting global animation options) doesn't seem to have any impact on the Frame Range rendered. This includes going into the Controls and manually setting it to 1-100. Obviously I'd prefer not having an additional 140 frames worth of empty at the end of the simulation :) Any tips to what might have gone wrong? (Houdini 17.5.173).

• allansimonsen 4 years, 10 months ago  |

Switched the range to using \$FSTART/\$FEND instead of RFSTART/RFEND (similar to the rop_pyro_preview node) seems to resolve it. I haven't ducked deeper into the system to see where else that might break things.

• hyawatha15 3 years, 10 months ago  |

Using Houdini 18 and I'm encountering a couple of problems with this.
1. No matter what the start and end range is set to, or images per line and Atlas Resolution is set to, the number of frames stays at 1 and tries to generate an (Images per Line) x 1 atlas.

2. When hitting Render at the top, nothing happens. When hitting Render Atlas, motion_vector_comp has the following error: Cook error in input: MV_COMP_OUT.

• hyawatha15 3 years, 10 months ago  |

An easy reproduction of these issues is to start with a blank file, create a sphere mesh and create an Explosion under the Pyro FX tab.

• mikelyndon-sesi 3 years, 10 months ago  |

Please update to the latest daily build of Labs. Some changes were made last week that may resolve your issue. Also, make sure you're pointing to the object level node, not the SOP level node.

• hyawatha15 3 years, 10 months ago  |

I have the latest tools (437). It seems to have corrected the atlas issue I was seeing, but I'm still seeing the MV_COMP_OUT error. From the simple steps I wrote above, I set /obj/pyro_import as the Export Node. Is that incorrect?
Thanks

• mikelyndon-sesi 3 years, 10 months ago  |

Could you move this conversation to the forum? Create a post in the realtime section . If you dive inside the ROP what is the error for MV_COMP_OUT?

• voooor 3 years, 10 months ago  |

my texture doesn't same you Something is painted more around the cloud How can I get a clean texture?

• mikelyndon-sesi 3 years, 10 months ago  |

That's an intended effect. The border pixels are expanded outwards to avoid artifacts in the distortion of the beauty texture.

• Gridz-sama 3 years, 9 months ago  |

Hey, a really good tutorial by the way.
- I'm having a bit of a problem with my output picture.
I can't import it because it makes an error in UE4 telling me I can't import it or it crashes my UE4 project.
- How to get all the frames of the pyro simulation on the same map ?
At the moment, all the frames are separated and doesn't look like the Motion Vector Map.
- The colors of my beauty are weird.
It is full of colour instead of the original colour.

I use Houdini 17.5 for some reason And the lastest version of UE4.

• mikelyndon-sesi 3 years, 9 months ago  |

Hi. Please move this conversation to the forum and post pictures of your setup and the result. It's really difficult to troubleshoot just based on the list of problems you're having.

• DRiz 3 years, 8 months ago  |

Hi! Is there any chance I could get the textures used in this video so we could replicate the results? Trying to get this to work in a different engine. :)

• DRiz 3 years, 8 months ago  |

Tip to others: I saw the textures were in the Labs github, they were in unity form, so I installed Unity to grab them.

• Noboru_Garcia 2 years, 7 months ago  |

Many of these amazing tools that generate a script for the material editor do not place the entire material into UE. Is there a better way to rebuild the materials? It seems like every new release the past function gets more and more broken. I really enjoy using your tools, it's this last step of getting it all rebuilt in UE that is difficult. Even a photo of what the completed material should look like can help.

• arima99 2 years ago  |

Hi guys. It seems like the video has deleted can someone tell me what should i do with raw multiplier? Where ever i searched in ue4 couldnt find "raw multiplier input of material function"

• Lee_zhang 1 year, 11 months ago  |

This video does not exist

• www847364963 2 months, 1 week ago  |

What are the laws of RGBA?