There are a few potential reasons of varying likelihood...

• Are the features in the same coordinate system?
• Is the HullAccumulator the best transformer? What shape is is producing?
• What predicate are you using in the SpatialRelator? I would think Requestor is Within Supplier is the one to go with.
• Is the SpatialRelator the best transformer to use? It returns a relationship attribute, which you don't seem to be testing. Perhaps the SpatialFilter would be better (to actually divide the point clouds into match/don't match)

I'm not sure what shape your LAS files are, but if they are rectangular in extents, then it might be better (more efficient and perhaps a better result) to simply get the min/max extents (PointCloudPropertyExtractor) and create a box/hull from that (2DBoxReplacer).

@badho

IF you have a grid file for the las, I would spatialrelate and then test for intersect using those.

Then feature reader to get the las files with the appropriate id from the related extents.. So you read the LAS after relating its extent.

If you don't have a predefined grid:

To get the extent I would indeed use a hull accumulator in convex mode. (there is no PointCloudExtentsCoercer (yet?))

Like @mark2atsafe said, get the extent and relate that. I would not do inside, for that would require the entire pc to be inside (1 or more of) your shapefile(s).

If you use something like Dutch AHN, then there is a grid in the metadata. (which I do use)

If it is a often used process I always first tile the pc, to acquire smaller pc's. This will save a lot of time, for instance when you need height of one single building you would only need to read a small(er) pc.

(just described how I do it..;)