[OSM-talk] Funding of three infrastructure projects : Nominatim, osm2pgsql, Potlatch 2
mwoehlke.floss at gmail.com
Tue Aug 4 14:26:17 UTC 2020
On 04/08/2020 08.10, Martin Koppenhoefer wrote:
> On 4. Aug 2020, at 13:58, Matthew Woehlke wrote:
>> but I would practically *kill* for JOSM to have FreeCAD's suite of sketch constraints ;-).
> you’re aware that there are sketch constraints for configurable
> angles (90, 60, 45 etc) and projection snaps? Hit 2 times „a“ (angle
> display becomes green)
Yes. They're better than nothing, but nowhere near what I'm talking
about. As an example, consider the attached simple FreeCAD sketch which
is roughly representative of some buildings I've mapped recently. The
dome in front is centered (segments on either side constrained to be
equal). The "wings" in back are symmetrical.
It's *possible* to do this sort of thing in JOSM with a lot of care and
by building part of the geometry, then constructing a bunch of "scratch"
geometry in order to construct a symmetry line, then doing a copy, paste
in place, mirror, reverse, stitch the parts together... but God help you
if you make a mistake and have to start over.
In FreeCAD, you just slap on some equality constraints, angle
constraints, parallel constraints, etc. and then you can *move* any of
the nodes and everything else will update to preserve the applied
constraints. (The one things it's missing that would be helpful is a
*colinear* constraint; you have to simulate that with parallel and
coincident constraints using "construction" lines; those are the blue
ones. A colinear constraint could eliminate the need for those
construction lines.) This is the major difference, though. In JOSM,
constraints only apply when you initially draw something, so if you get
it wrong, you have to start over. In FreeCAD, they're a dynamic system;
if you get it wrong, just nudge it and the whole thing updates *while
preserving your constraints*.
Oh, and *arcs*. The ability to define a segment that should be a perfect
arc, and optionally make it tangent or perpendicular to its neighbors,
would be a major boon. Again, I can fake it with a bunch of scratch
construction, but if it's wrong, I have to start over and hope my next
guess is better. In FreeCAD, just drag the end points until it looks right.
Then there are distance constraints, which would be incredibly useful if
you're mapping something with known dimensions.
Seriously, give FreeCAD a spin. It's pretty awesome for this sort of
relatively simple 2D stuff. Also look at some of the buildings I've done
recently; the symmetrical ones don't just *look* symmetrical, they *are*
symmetrical (within the limits of JOSM's abilities). I've also done a
lot of stuff like roads that are perfectly centered in between parking
spaces, groups of aligned buildings that are *actually* aligned, and
whatnot. It's do-able, but it would be *soooo* much easier with
Obviously, this would all almost surely be a temporary mode (maybe it
persists as long as JOSM is open, but isn't uploaded), but since you
usually draw once, that would be fine. (Bonus points if JOSM could
automatically recreate constraints for ways that don't have any. It
shouldn't be hard to guess equality, perpendicular and colinear
constraints, at least.)
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 23478 bytes
Desc: not available
More information about the talk