[pgrouting-dev] A roadmap

Tue Apr 3 14:41:57 PDT 2018

The Roadmap looks good to me.  Should make some sections of pgRouting book obsolete and allow us to cover other topics.

*withPoints functions are very popular, but I think there has to be a simpler way of coming up with the  point/frac  as that's where I think most people struggle.

But unfortunately I don't have any thoughts about that yet and haven't looked at recent functions added.  

As far as getting rid of CGAL not sure how important that is.  I think a lot of package maintainers are used to having that dependency now and for Windows, I need to include CGAL anyway to support PostGIS SFCGAL.

There is also some talk of expanding CGAL use in PostGIS.  That said, if the alpha shape rewriting is a lot of work, I'd put it off, as the gain would have been useful a couple of years ago, but not so much today.

Thanks,

Regina

From: pgrouting-dev [mailto:pgrouting-dev-bounces at lists.osgeo.org] On Behalf Of Vicky Vergara
Sent: Tuesday, April 03, 2018 11:37 AM
To: pgRouting developers mailing list <pgrouting-dev at lists.osgeo.org>
Subject: [pgrouting-dev] A roadmap

Hello fellow developers,

As you know we are rewriting pgRouting, since v2.1, to remove all "bugs", like the non standard way of constructing a graph, and using more C++ features.

The rewrite is "almost done":

**First pair of functions**

*        pgr_alphaShape - Alpha shape computation

*        pgr_pointsAsPolygon - Polygon around a set of points

Both functions are tightly dependant, and I believe that they should be a postGIS function as is a geometry function, and the closest one that resembles this pair of functions is  ST_ConcaveHull [1] Some time ago I compared both functions on [2] 

I went to see how to add that function to postGIS, and for the moment that is not possible, it sould be done first in GEOS, and  GEOS is so big, right now I dont feel is the time to do that, but rewriting to use boost:Geometry would eliminate the need of CGAL, so one less pre-requisite to build pgRouting would be needed. or they can stay as they are now.

**The other function is pgr_trsp**

Which has so many problems at postgres level [4], Last year on GSoC, Vidham tried to do a rewrite, confirming that the problem is much harder than expected for the 3 month program. But as far as I know many people use them because it has the "points" version.

The C++ code is not well designed [5], just a look at that, my_dijkstra calls my_dijkstra and that calls my_dijkstra, it still uses pointers, so great chance of memory leaks, etc.

Basically is **Use at your own risk**

Beside those functions mentioned above, now we are in the moment where there are  more proposed functions [7] than official functions. and a lot of deprecated functions that have to be maintained and tested because of backwards compatibility.

** So, here is my road map #1 **

Version 2.7 to be released on September 2018 where fix bug of pgr_withPoints [8] is a must have, and the possibilities of what other things it could have:

- New functionality done by GSoC students on "experimental section"

- Write a substitution (with a different name maybe pgr_dijkstraTR) for pgr_trsp (one vertex to one vertex) based on dijkstra

- Rewrite pgr_alphaShape to use boost:graph instead of CGAL

- move some experimental functions up to proposed

Version 3.0 I would like it to be on September 2019

Where a complete cleanup of the deprecated functions would be done,

Move proposed functions to official pgRouting functions.

** So, here is my road map #2 **

Version 3.0 to be released on March 2019 where fix bug of pgr_withPoints [8] and Complete cleanup of the deprecated functions are a must have, and the possibilities of what other things it could have:

- New functionality done by GSoC students on "experimental section"

- Write a substitution (with a different name maybe pgr_dijkstraTR) for pgr_trsp (one vertex to one vertex) based on dijkstra

- Rewrite pgr_alphaShape to use boost:graph instead of CGAL

- move some experimental functions up to proposed

- Move proposed functions to official pgRouting functions.

Probably this second road map will make the second version of the pgRouting book a little easier to write, (please Robe, comment on this)

We would like comments from the community about both road maps and if possible  to test proposed functions and experimental functions to help decide which proposed functions can go up one level. (don't forget to open issues)

Regards

pgRouting team

[1] https://postgis.net/docs/ST_ConcaveHull.html
[2] https://github.com/cvvergara/pgrouting/issues/57
[3] https://github.com/pgRouting/pgrouting/blob/master/sql/alpha_shape/alpha_shape.sql#L62
[4] https://github.com/pgRouting/pgrouting/tree/master/doc/trsp

[

5] https://github.com/pgRouting/pgrouting/blob/master/include/trsp/GraphDefinition.h#L94

[

6] https://github.com/pgRouting/pgrouting/tree/master/sql/pickDeliver

[

7] http://docs.pgrouting.org/latest/en/proposed.html
[8] https://github.com/pgRouting/pgrouting/issues/760

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Vicky Vergara
Operations Research

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