Variation in coordinate values

[mghildiy]

I am rendering a point cloud from LAS file.
During debugging of render.js's ParticleSystemBatcher.prototype.push method, I found that points added to particle system have coordinate values always positive. And Z component for most of the points is in range of 8-10 units.

Rendered scene is as:

Red axis is X, green axis is Y and blue axis is Z.
As can be seen, coordinate values along all three are both positive and negative. And along Z, coordinate values are very small(image 2), while I found it to be in range of 8-10 during debugging.
What causes this variation?

[hbs]

I also notice weird Z values, they seem to be rounded as my points appear in layers when they really should be distributed across the Z axis. Any reason for this behavior?