Aligning particle emitting from the z-axis while resizing

[LerpSoh (MattressBuyer)]

1. What do you want to achieve? Keep it simple and clear!
   I want to be able to align particle emitter that are emitting from the z-axis while it resizing.
   A goggle image to show what I mean:
   

   
   
   As you see the quad or the face made up by the yellow line is the particle and I want the particle to resize like that.

2. What is the issue? Include screenshots / videos if possible!
   Everything keep overlapping and make stuff too bright.

3. What solutions have you tried so far? Did you look for solutions on the Developer Hub?

Currently I have try everything particle emitter have to offer, I can’t change the maximum size due to foreshortening effect so it must always be the highest which is 10 and a minimum size of 2.
I have try the acceleration property but it so darn hard to control and I don’t know any equation and am bad at making equations.

I have taken a look of Tracking Roblox Particles but it still too confusing for me to do.

I have try making the froxelHost from Dynamic volumetrics in Roblox - Technical Fluff which is: “each line of froxels at a given X and Y index can be represented as a single particle system travelling from the near plane to the far plane”(I don’t know how to rephrase this better). Which I do this:

It used to be a plane and also it seem very wrong from the video: https://www.youtube.com/watch?v=b0jQH852u9s

As first I was gonna switch to billboardGui but the light emission property is just missing and I would also need it to move like particle to catch light when the spacing is too big or the light range is too small, it doesn’t behave the same, light emission are 0, transparency 0.5, billboardGui scale is 2 studs I think while particle is 1.
Light shadow off:

Light shadow on:

The particle do overlap but it still way brighter than billboardGui

I have also try to align the orientation of the particle emitter like the fov but well it goes to the first problem. I try going for the farer the attachment from the froxelHost the bigger the particle get but the small particle just overlap again and just give unnatural brightness.

I haven’t try to message Elttob not because I want too but because the technique is literally here Dynamic volumetrics in Roblox - Technical Fluff at the Sacrificing control for light catching optimisations but I just can’t figure out the scaling and aligning.

Best I can achieve:

[LerpSoh (MattressBuyer)]

Turn out it was to use pythagorean theorem I wish I spend more time looking far and wider. Also apologize for the post if it sound rude or rush I was writing it when it was over midnight and I am extremely frustrated because I can’t get this done but oh well.