GEOSSnap: Preserve Z values from input

[dbaston]

No description provided.

[dbaston]

Need to compare w/JTS and desired behavior. If the geometry to which we snap has Z values, should the snapped geometry assume them?

[dr-jts]

Need to compare w/JTS and desired behavior.

JTS doesn't address this.

If the geometry to which we snap has Z values, should the snapped geometry assume them?

Makes sense to me

[dbaston]

It appears that JTS does handle this. It takes the Z value from the snapped-to point.

bin/jtsop.sh -a "LINESTRING Z (0.99 0.99 4, 5 5 8)" -b "POINT (1 1 999)" Snapping.snapAtoB 0.1 -f wkt
LINESTRING Z(1 1 999, 5 5 8)

also

bin/jtsop.sh -a "LINESTRING (0.99 0.99, 5 5)" -b "POINT (1 1 999)" Snapping.snapAtoB 0.1 -f wkt
LINESTRING Z(1 1 999, 5 5 NaN)

but

bin/jtsop.sh -a "LINESTRING (5 5, 0.99 0.9)" -b "POINT (1 1 999)" Snapping.snapAtoB 0.1 -f wkt
LINESTRING (5 5, 0.99 0.9)

(after patching GeometryOutput.java to print Z values)

[dr-jts]

It appears that JTS does handle this. It takes the Z value from the snapped-to point.

That make sense, because the snapped-to point is copied. What about if the snapped point is the one that carries the Z value? A quick inspection of the code makes me think that won't work.

But of course that may or may not be desirable.