select spline segments by direction (i.e. only vertical or horizontal segments)

[super gnu]

well a lot of my posts seem to be about dealing with really messy models.

in this case a city model without a landscape mesh... i just have the buildings as lowpoly boxes, open at the bottom. of course they are all at different heghts.


i had the idea to select all outlines (hence getting the open edges at the bottoms)

generate splines from them, then try various terrain generation tools to skin between them to generate the topology.


however of course there are turned faces, unwelded vertices and other nasties in the building meshes. so, when i select the outlines, and generate splines from them,, i also get some vertical lines as well as the horizontal building outlines.


i want to select only the vertical (z axis) segments of the splines, and delete them. hopefully this will leave me with only the horizontal building footprints, and hopefully i can generate a terrain mesh from them somehow.


what a mess :P

any suggestions?

ive tried every combination of the graphite selection tools to select only those bottom edges, but no combination works well. i always get some vertical edges and a few top ones in the selection.


bearing in mind its a few dozen sq km of buildings, its not practical to do any manual work really.

[wxyz]

Cap the bottom borders and remove these caps and isolate them. Drape a cloth sim over the isolated objects?

[super gnu]

if i could select only the bottom borders id be well on my way, but as mentioned, there are small gaps/flipped faces/ unweldable bits, basically meaning the borders often extend a few thin lines vertically up the side of the buildings, sometimes even a loop around part of the roof, although this is rare.

i can generate a spline from these edges, and try to run a terrain compound on it, and if i do it on a small section it works (but obviously wrong because of vertical elements) , but strangely it seems that even opening the "compound objects" rollout involves some kind of analysis of the object selected, as it basically hangs max if i a) try to go to the "compound objects" rollout with the whole spline object selected, or b) try to select the whole spline object whilst in the "compond objects" menu.

ive left it overnight but its still frozen in the morning, and ram usage is static. so im guessing its a real crash.

ive cleaned the building geometry up as much as possible using whatever global tools are available, (originally -all- the roofs were flipped and all vertices unwelded) but with over 10,000 buildings i wont be doing any manual cleaning.


as in my original post, if i could take my generated splines, and select all the segments that are aligned vertically and delete them, id be a lot closer to something usable... maybe...