# Simulating a laser show?

Just increase the ‘Amount’ parameter of the circle (the spot) above 1.0. Make it extremely hight would ruin the laser effect, though so try with something like 10 to 20 initially. To make tests faster follow those tips:

1. Use low resolution on canvas.
2. Use quality 8 on canvas.
3. Render only one frame (one relevant frame) to high resolution for testing purposes.
4. Never use anti-aliasing more than 1. It is not noticeable.
5. Do not increase Subsampling factor so much unless you need it in the final render. Remember that final render would increase subsampling when quality is better (1) and would leave subsampling to its lower value when quality is 9. The multiplicaiton factors of subsampling depending on quality and are those:

quality = 1 samples=32
quality = 2 samples=24
quality = 3 samples=16
quality = 4 samples=12
quality = 5 samples=7
quality = 6 samples=6
quality = 7 samples=5
quality = 8 samples=3
quality = 9 samples=2
quality = 10 samples=1

final samples = samples * subsamples_factor

So if you don’t modify the subsampling factor, you get 32 samples per frame in the final render (q=1) but would work with 3 samples in canvas window (q=8).

The transparency of each sample of the spot is obtained dividing the Amount parameter by the number of samples. For steady objects the final transparency is the overlapping of the N samples with a transparency of Amount/N so finally it is the same transparency than the original object. Well, this is a simplification for constant interpolation.
So if the object that is blurred under movement is steady and you use a big amount, it would become very non transparent (above the normal 1.0) and so, the anti-aliasing would fail, creating non fine edges around the object.
Solution, increase Amount only when spot is in movement and increase more if it moves faster.

Another tip, the faster the movement, the larger the trail of the object but less bright. Aperture parameter creates the illusion of a faster object, subsampling factor makes it more persistent (smooth transitions), and Amount of the object makes it brighter.

-G

Thank you for the detailed reply. This sort of thing is what makes a program like Synfig viable, even if there are other weakness with documentation.

I will try this the next opportunity to devote a few hours.

-Joe