Comments on: Improving PhotoSynth extension performance

By: Henri

Henri — Tue, 01 May 2012 18:24:29 +0000

@Bart: thanks for the tip but in fact this is an old optimization that is no longer valid (js engine have optimized string concat now: you can check this jsperf for example). I have described the solution I end up with in my next post. The big issue was in fact the memory usage and the high number of temporary object created and garbage collected. So writing directly in a binary array was the only way to keep memory usage low (AFAIK).

By: Bart

Bart — Tue, 01 May 2012 17:14:54 +0000

> Sadly I didn’t manage to find a way to accelerate
> “bundle.out” ascii file generation yet (involving lot of
> string concatenation and numbers formatting).

Have you tried postponing the concatenation? Just push the data into an array first (these can be pre-formatted substrings, e.g. an array element for each camera, or for each line). When done, just use the join function of the array.

Ex:
var a = ["this","is","an","example"];
var s = a.join(” “); // or a.join(“\n”) for newlines

This should be a lot faster, because it only needs one concat (creating the joined string) instead of creating a newly concatenated string every time, copying the old string data plus the newly added sub string…

By: WebGL Photosynth extension updated » Visual-Experiments.com

WebGL Photosynth extension updated » Visual-Experiments.com — Sun, 25 Mar 2012 21:08:16 +0000

[...] my PhotoSynth extension for Google Chrome. I’ve included all optimization described in my previous post: point cloud loading is 4x faster and ply file generation could be 17x faster in some cases . As [...]