Motion blur isn't making things blurry. It's integrating data over a time interval.

Ask yourself: Is my geometry changing?

NO: Go to Constant Geometry Section

    (Keyframed moving stuff or animated geometry driven by bones)

    Method 1: Geometry Blur using Karma LOP Cache (Recommended)
    Method 2: Velocity Blur
    Method 3: Acceleration Blur

YES: Go to Changing Geometry Section

     (Like Particles)

     Method 1: Base Velocity or Acceleration
     Method 2:  Using SOP Particle Trails

BONUS: Camera Blur

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BUT WHY? I’ve been told to use @v

Recommended Blur using Lop Cache

Acceleration Blur

Velocity Blur

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CRUCIAL 1 YOU NEED TO HAVE FLOAT FRAMES $FF not INTEGER FRAMES $F

Dude what? You need to have information between frames, for that you have to animate using $FF instead of $F or if for some reason you can’t or if you are importing an animation from another source you have to place a SOP RETIME after your animation to interpolate and create that “missing” information between frames. Set the interpolation to Cubic (just do it) Your animated Stuff > SOP Retime > OUTPUT

**You can also replace $F with $FPS*$T+1**

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CRUCIAL 2 TO RENDER IT PROPERLY

USING ONLINE CACHE (which you probably are) Inside your LOP USDRENDER_ROP you have to go to Output > Usd Export > Filter Time Samples > Change it to Never (By default it will be set on Always)

or if you are using OFFLINE CACHE that is to say saving and loading your animation with a LOP FILE CACHE: You need to save the animation with Substeps then you con leave Filter Time Stamps as default.

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CONSTANT GEOMETRY (NO CHANGES IN THE GEOMETRY)

You don’t need velocity or Acceleration blur if you geometry is not changing when rendering in Karma. I’ll explain them but if you geometry is not changing the best method that you can use is explained below

Method 1 (Recommended)

Inside Solaris Add a LOP CACHE after the object that you want to have motion blur

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You need to match the Shutter Speed with your camera settings

In this case the Shutter Open and Shutter Close values are references from the LOP Camera

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Use at least 3 samples in the LOP Cache node, to have at least 3 points of reference for the blur

The higher the sampler the better the transition

3 Samples, you can see the angular transition

6 Samples, Smoother Transition

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LOP Karma Render Settings > Rendering > Camera Effects > Enable Motion Blur (Leave rest as default)

METHOD 2 - Velocity Blur @v

LOP Karma Render Settings > Rendering > Camera Effects > Enable Motion Blur > Velocity Blur > Velocity Blur

For this to work you need the Vector Attribute @v

You can get it by many different ways, for example using SOP Compute Velocity after your animation

METHOD 3 - Acceleration Blur @accel

You need a way to compute v@accel for example, place a SOP Point Velocity after your animation

In your LOP Karma Render Settings > Rendering > Camera Effects > Motion Blur Enabled > Velocity Blur > Acceleration Blur Geometry Time Samples: At least 3

Geometry Time Samples 2

Geometry Time Samples 3, better transition

NOT CONSTANT GEOMETRY

Notice how in SOP Point Velocity > Match by Attribute is enabled