PostGIS 2.0 Wishlist
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PostGIS 2.0 Wishlist
by Paul Ramsey
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FYI, I'm working on the overall wishlist document at this URL:
http://docs.google.com/Doc?id=dg99qr76_2dgt26j -- Paul Ramsey Refractions Research http://www.refractions.net pramsey@... Phone: 250-383-3022 Cell: 250-885-0632 _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Paul Ramsey
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I've been updating this throughout the day, so it's more interesting
now. Still more interestingness to come. On 23-Apr-07, at 12:32 PM, Paul Ramsey wrote: > FYI, I'm working on the overall wishlist document at this URL: > > http://docs.google.com/Doc?id=dg99qr76_2dgt26j > -- > > Paul Ramsey > Refractions Research > http://www.refractions.net > pramsey@... > Phone: 250-383-3022 > Cell: 250-885-0632 > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Anton Patrushev-2
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Hi Paul,
I am the one who are making pgRouting. So, if you need any help with it, just ask me. Thanks, Anton A. Patrushev Software Engineer Orkney, Inc. 6F JA-Kyosai Yokohama Building, 1-2 Kaigandori, Naka, Yokohama 231-0002 JAPAN Tel 81-45-228-3320 Fax 81-45-228-3321 www.orkney.co.jp > I've been updating this throughout the day, so it's more interesting > now. Still more interestingness to come. > > On 23-Apr-07, at 12:32 PM, Paul Ramsey wrote: > >> FYI, I'm working on the overall wishlist document at this URL: >> >> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >> -- >> >> Paul Ramsey >> Refractions Research >> http://www.refractions.net >> pramsey@... >> Phone: 250-383-3022 >> Cell: 250-885-0632 >> _______________________________________________ >> postgis-users mailing list >> postgis-users@... >> http://postgis.refractions.net/mailman/listinfo/postgis-users > > > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Anton Patrushev-2
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Oops, sorry for weird English :)
New version of pgRouting is available for download from www.postlbs.org since 24th of April. It has shiny new shortest path function for real road networks with turn restrictions and traffic lights. I hope you will like it. Anton. > Hi Paul, > > I am the one who are making pgRouting. > So, if you need any help with it, just ask me. > > Thanks, > Anton A. Patrushev > Software Engineer > Orkney, Inc. > 6F JA-Kyosai Yokohama Building, > 1-2 Kaigandori, Naka, Yokohama 231-0002 JAPAN > Tel 81-45-228-3320 Fax 81-45-228-3321 > www.orkney.co.jp > >> I've been updating this throughout the day, so it's more interesting >> now. Still more interestingness to come. >> >> On 23-Apr-07, at 12:32 PM, Paul Ramsey wrote: >> >>> FYI, I'm working on the overall wishlist document at this URL: >>> >>> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >>> -- >>> >>> Paul Ramsey >>> Refractions Research >>> http://www.refractions.net >>> pramsey@... >>> Phone: 250-383-3022 >>> Cell: 250-885-0632 >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@... >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >> >> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@... >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist - PgRouting 1.0.0.a
by TECHER David
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Hi Anton,
Very interesting :) ! I've just tried to install it on my Ubuntu Dapper...no problem :) When I've got enough time, I will try the Shooting* function. Or do U have any doc for that? Kin regards. David. Anton A. Patrushev a écrit : > Oops, sorry for weird English :) > > New version of pgRouting is available for download from > www.postlbs.org since 24th of April. > It has shiny new shortest path function for real road networks with > turn restrictions and traffic lights. > > I hope you will like it. > > Anton. > >> Hi Paul, >> >> I am the one who are making pgRouting. >> So, if you need any help with it, just ask me. >> >> Thanks, >> Anton A. Patrushev >> Software Engineer >> Orkney, Inc. >> 6F JA-Kyosai Yokohama Building, >> 1-2 Kaigandori, Naka, Yokohama 231-0002 JAPAN >> Tel 81-45-228-3320 Fax 81-45-228-3321 >> www.orkney.co.jp >> >>> I've been updating this throughout the day, so it's more >>> interesting now. Still more interestingness to come. >>> >>> On 23-Apr-07, at 12:32 PM, Paul Ramsey wrote: >>> >>>> FYI, I'm working on the overall wishlist document at this URL: >>>> >>>> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >>>> -- >>>> >>>> Paul Ramsey >>>> Refractions Research >>>> http://www.refractions.net >>>> pramsey@... >>>> Phone: 250-383-3022 >>>> Cell: 250-885-0632 >>>> _______________________________________________ >>>> postgis-users mailing list >>>> postgis-users@... >>>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >>> >>> >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@... >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@... >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users > ___________________________________________________________________________ Yahoo! Mail réinvente le mail ! Découvrez le nouveau Yahoo! Mail et son interface révolutionnaire. http://fr.mail.yahoo.com _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist - PgRouting 1.0.0.a
by Anton Patrushev-2
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Hi David,
Yeah, I know. Thank you for your tutorial! :) Well, I wrote few words in README.routing file... But I guess it is not so helpfull :) So, it works almost like A* with several differences: 1. It calculates a path from edge to edge (not from vertex to vertex) 2. You need 2 more columns - rule (varchar) and to_cost (double precision). For example, gid | source | target | cost | x1 | y1 | x2 | y2 | to_id | to_cost | rule -----+--------+--------+------+----+----+----+----+-------+---------+------ 12 | 3 | 10 | 2 | 4 | 3 | 4 | 5 | | 1000 | 14 means that cost of going from edge 14 to edge 12 is 1000, and gid | source | target | cost | x1 | y1 | x2 | y2 | to_id | to_cost | rule -----+--------+--------+------+----+----+----+----+-------+---------+------ 12 | 3 | 10 | 2 | 4 | 3 | 4 | 5 | | 1000 | 14, 4 means that cost of going from edge 14 to edge 12 through edge 4 is 1000. Indeed, I should write better readme :) Anton. > Hi Anton, > > Very interesting :) ! > > I've just tried to install it on my Ubuntu Dapper...no problem :) > > When I've got enough time, I will try the Shooting* function. > > Or do U have any doc for that? > > Kin regards. > > David. > > Anton A. Patrushev a écrit : > >> Oops, sorry for weird English :) >> >> New version of pgRouting is available for download from >> www.postlbs.org since 24th of April. >> It has shiny new shortest path function for real road networks with >> turn restrictions and traffic lights. >> >> I hope you will like it. >> >> Anton. >> >>> Hi Paul, >>> >>> I am the one who are making pgRouting. >>> So, if you need any help with it, just ask me. >>> >>> Thanks, >>> Anton A. Patrushev >>> Software Engineer >>> Orkney, Inc. >>> 6F JA-Kyosai Yokohama Building, >>> 1-2 Kaigandori, Naka, Yokohama 231-0002 JAPAN >>> Tel 81-45-228-3320 Fax 81-45-228-3321 >>> www.orkney.co.jp >>> >>>> I've been updating this throughout the day, so it's more >>>> interesting now. Still more interestingness to come. >>>> >>>> On 23-Apr-07, at 12:32 PM, Paul Ramsey wrote: >>>> >>>>> FYI, I'm working on the overall wishlist document at this URL: >>>>> >>>>> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >>>>> -- >>>>> >>>>> Paul Ramsey >>>>> Refractions Research >>>>> http://www.refractions.net >>>>> pramsey@... >>>>> Phone: 250-383-3022 >>>>> Cell: 250-885-0632 >>>>> _______________________________________________ >>>>> postgis-users mailing list >>>>> postgis-users@... >>>>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> postgis-users mailing list >>>> postgis-users@... >>>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>>> >>> >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@... >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@... >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > > > > > > ___________________________________________________________________________ > Yahoo! Mail réinvente le mail ! Découvrez le nouveau Yahoo! Mail et > son interface révolutionnaire. > http://fr.mail.yahoo.com > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by ValiSystem
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On 23 avr. 07, at 21:32, Paul Ramsey wrote: > FYI, I'm working on the overall wishlist document at this URL: > > http://docs.google.com/Doc?id=dg99qr76_2dgt26j > -- > > Paul Ramsey > Refractions Research > http://www.refractions.net > pramsey@... > Phone: 250-383-3022 > Cell: 250-885-0632 Hello, I saw that you plan a nearest neighbor implementation for PostGIS 2.0. Last year, two students worked for me on that subject, i've been thinking to give you the result (my company owns the copyright, and we don't plan to do any business with this stuff), but i wanted to do a cleanup, checking the code and do some improvement before posting it. But i didn't take the time, and be sure that i'm sorry. I've been talking about that last month on IRC, to see if someone were interested, someone answered positive, but i'm on a rush a work and i did not worried about that anymore. Anyway, the algorithm is the Hjaltason & Samet one [1], and as far a i tested it, it was pretty good. But the current implementation has many problems : - it's all commented in french, and even some parts of code are in french (damned students) - the implementation works only with BBOXes, and not the actual geometry. AFAIK it could be possible to use the distance() function, but it needs to plays with datatypes to find the accurate implementation. - the function is not integrated to postrgesql correctly, you cannot use it in query, only in one call, where you give tables names, etc as parameters and even some attributes name might be hard coded. Nothing critical, but dirty job to be done. - it has been written somewhat quickly, by novice programmers. But, the good news are : - there has been a worry of quality, since the student took care to write it in VC1 by himself. - it has worked correctly without visible bug on a 100 000 rows table in a small amount of time (i don't remember the exact values of the benchmark). For the ones who are interested, the algorithm used is a kNN one (k Nearest Neighbors), so that you can get one or several results, ordered by distance. To sum up quickly, the general algorithm plays with the R-Tree, it explores it in depth (choosing the correct branches), and fill in an array while going back up. When the R-Tree structure has been explored enough to ensure that the returned list is effectively the kNN ones (obvious, but an R-Tree is a quite tricky structure, so, not so easy to ensure :) ) the algorithm finishes. So, I don't know if anyone is really interested with that piece of code, but, just in case, because it may avoid some hours of hard work. Anyway if someone wants to use it, it's pretty sure that i'll give some help. I didn't do that by myself, but i'd be happy to work with someone. Nicolas. [1] not sure, but i think that it is this one : http:// citeseer.ist.psu.edu/hjaltason98incremental.html _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Rob Agar-2
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Paul Ramsey wrote:
> FYI, I'm working on the overall wishlist document at this URL: > > http://docs.google.com/Doc?id=dg99qr76_2dgt26j My 2c: it would be a *great* help to new users to expand the existing documentation. The single most helpful thing would be explicit information about the data types of function parameters and return values. Improving the navigation wouldn't hurt either :) Rob _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Martin Spott
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Paul Ramsey wrote:
> FYI, I'm working on the overall wishlist document at this URL: > > http://docs.google.com/Doc?id=dg99qr76_2dgt26j While topology/routing certainly would be a very nice add-on to PostGIS, it would already be helpful for several cases being able to define what I'd call a "junction" or a connection between two geometries. I'm not fluent in these special terms, so please excuse if my explanation sounds a bit weird - feel free to translate it into your own words .... ;-) Let A be a polygon and B a linestring. At the location O there is a vertice in A as well as a node in B - O makes the logical connection between these two. If the node in B at the location O is being relocated, then the vertice in A at the location O should be moved as well: /-----\ A | | \--O--/ | | B \ \ I know that such function would have to be backed by certain contraints (what is supposed to happen if I remove the node in B at O). Just because it's a bit complex I _do_ see a noticeable value in puttin such feature onto the wish list for PostGIS - instead of implementing the whole thingie in SQL procedures. Cheers, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -------------------------------------------------------------------------- _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Yeroc
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Paul,
Maybe this has been addressed already but is there any chance of having PostGIS properly handle geometries that cross the antimeridian (+/-180 longitude) and the poles? See this thread (http://www.nabble.com/polygons-crossing-0-360-longitude-tf1820863.html) for more details. Corey
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Re: PostGIS 2.0 Wishlist
by Paul Ramsey
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It's something we hope for funding for, but absent that will probably be
low down the priority list, since it is a relatively rare use case. Adding more geodetic functions (area, buffer, distance) seems like a higher priority than handing the geodetic singularity points. P Yeroc wrote: > Paul, > > Maybe this has been addressed already but is there any chance of having > PostGIS properly handle geometries that cross the antimeridian (+/-180 > longitude) and the poles? See this thread > (http://www.nabble.com/polygons-crossing-0-360-longitude-tf1820863.html) for > more details. > > Corey > > > Paul Ramsey wrote: >> FYI, I'm working on the overall wishlist document at this URL: >> >> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >> > -- Paul Ramsey Refractions Research http://www.refractions.net pramsey@... Phone: 250-383-3022 Cell: 250-885-0632 _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by pcreso
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--- Paul Ramsey <pramsey@...> wrote:
> It's something we hope for funding for, but absent that will probably be > low down the priority list, since it is a relatively rare use case. > Adding more geodetic functions (area, buffer, distance) seems like a > higher priority than handing the geodetic singularity points. > > P Heavy sigh!! It might be rare for some, but 2 out of three datasets I use are a problem due to this issue. Various lists seem to have this problem pop up regularly, noteably around Alaska & New Zealand for some reason :-) At least PostGIS has better tools than most to work around it. GMT seems to do it best, it may be worth looking at how they deal with this & re-use their code/approach? Cheers, Brent Wood > > Yeroc wrote: > > Paul, > > > > Maybe this has been addressed already but is there any chance of having > > PostGIS properly handle geometries that cross the antimeridian (+/-180 > > longitude) and the poles? See this thread > > (http://www.nabble.com/polygons-crossing-0-360-longitude-tf1820863.html) > for > > more details. > > > > Corey > > > > > > Paul Ramsey wrote: > >> FYI, I'm working on the overall wishlist document at this URL: > >> > >> http://docs.google.com/Doc?id=dg99qr76_2dgt26j > >> > > > > > -- > > Paul Ramsey > Refractions Research > http://www.refractions.net > pramsey@... > Phone: 250-383-3022 > Cell: 250-885-0632 > _______________________________________________ > postgis-users mailing list > postgis-users@... > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Gregory Williamson
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Brent Wood wrote:
> --- Paul Ramsey <pramsey@...> wrote: > > >> It's something we hope for funding for, but absent that will probably be >> low down the priority list, since it is a relatively rare use case. >> Adding more geodetic functions (area, buffer, distance) seems like a >> higher priority than handing the geodetic singularity points. >> >> P >> > > Heavy sigh!! > > It might be rare for some, but 2 out of three datasets I use are a problem due > to this issue. > > Various lists seem to have this problem pop up regularly, noteably around > Alaska & New Zealand for some reason :-) > > At least PostGIS has better tools than most to work around it. > > GMT seems to do it best, it may be worth looking at how they deal with this & > re-use their code/approach? > > > Cheers, > > Brent Wood > Likewise here -- we have some work-arounds, but that's exactly what they are. Dateline issues mainly -- but I know I've seen issues with polar regions as well. OTH our engineers haven't conjured up suggestions for functions that haven't already been made, and none of those seem to be a high priority. (Is there geld for this work is another question ... our new corporate owners have more need for dateline / polar areas than did our core business at GlobeXplorer, which was more US/Euro-centric (but there are US possessions and parts of Alaska that do cross the dateline) but I also have no idea if they are open to funding OS. I can always ask I guess, if there's enough other interest. Greg Williamson Senior DBA GlobeXplorer, a DigitalGlobe company > > > > > > >> Yeroc wrote: >> >>> Paul, >>> >>> Maybe this has been addressed already but is there any chance of having >>> PostGIS properly handle geometries that cross the antimeridian (+/-180 >>> longitude) and the poles? See this thread >>> (http://www.nabble.com/polygons-crossing-0-360-longitude-tf1820863.html) >>> >> for >> >>> more details. >>> >>> Corey >>> >>> >>> Paul Ramsey wrote: >>> >>>> FYI, I'm working on the overall wishlist document at this URL: >>>> >>>> http://docs.google.com/Doc?id=dg99qr76_2dgt26j >>>> >>>> >> -- >> >> Paul Ramsey >> Refractions Research >> http://www.refractions.net >> pramsey@... >> Phone: 250-383-3022 >> Cell: 250-885-0632 _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Nicolas Ribot
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> Likewise here -- we have some work-arounds, but that's exactly what they
> are. Dateline issues mainly -- but I know I've seen issues with polar > regions as well. OTH our engineers haven't conjured up suggestions for > functions that haven't already been made, and none of those seem to be a > high priority. (Is there geld for this work is another question ... our > new corporate owners have more need for dateline / polar areas than did > our core business at GlobeXplorer, which was more US/Euro-centric (but > there are US possessions and parts of Alaska that do cross the dateline) > but I also have no idea if they are open to funding OS. I can always ask > I guess, if there's enough other interest. > French Space Agency (CNES) is also very interested by adding geocentric support into PostGIS. We (camptocamp) are in touch with them to fund a survey to estimate the amount of work needed to do so. We will keep the list posted about this project. Nicolas Ribot - CampToCamp. _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Frank Warmerdam-2
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Nicolas Ribot wrote:
>> Likewise here -- we have some work-arounds, but that's exactly what they >> are. Dateline issues mainly -- but I know I've seen issues with polar >> regions as well. OTH our engineers haven't conjured up suggestions for >> functions that haven't already been made, and none of those seem to be a >> high priority. (Is there geld for this work is another question ... our >> new corporate owners have more need for dateline / polar areas than did >> our core business at GlobeXplorer, which was more US/Euro-centric (but >> there are US possessions and parts of Alaska that do cross the dateline) >> but I also have no idea if they are open to funding OS. I can always ask >> I guess, if there's enough other interest. >> > > French Space Agency (CNES) is also very interested by adding > geocentric support into PostGIS. > We (camptocamp) are in touch with them to fund a survey to estimate > the amount of work needed to do so. > > We will keep the list posted about this project. > > Nicolas Ribot - CampToCamp. Nicolas, I believe PROJ.4 already supports geocentric coordinate systems, so in theory it should be as simple as adding a new entry in the spatial_ref_sys table associating an SRS ID with the PROJ.4 definition. eg (at proj.4 commandline): cs2cs +proj=latlong +datum=WGS84 +to +proj=geocent -117 33 -2430880.68 -4770871.97 3453958.64 Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@... light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | President OSGeo, http://osgeo.org _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by ValiSystem
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On 9 mai 07, at 15:04, Frank Warmerdam wrote: > Nicolas Ribot wrote: >>> Likewise here -- we have some work-arounds, but that's exactly >>> what they >>> are. Dateline issues mainly -- but I know I've seen issues with >>> polar >>> regions as well. OTH our engineers haven't conjured up >>> suggestions for >>> functions that haven't already been made, and none of those seem >>> to be a >>> high priority. (Is there geld for this work is another >>> question ... our >>> new corporate owners have more need for dateline / polar areas >>> than did >>> our core business at GlobeXplorer, which was more US/Euro-centric >>> (but >>> there are US possessions and parts of Alaska that do cross the >>> dateline) >>> but I also have no idea if they are open to funding OS. I can >>> always ask >>> I guess, if there's enough other interest. >>> >> French Space Agency (CNES) is also very interested by adding >> geocentric support into PostGIS. >> We (camptocamp) are in touch with them to fund a survey to estimate >> the amount of work needed to do so. >> We will keep the list posted about this project. >> Nicolas Ribot - CampToCamp. > > Nicolas, > > I believe PROJ.4 already supports geocentric coordinate systems, so in > theory it should be as simple as adding a new entry in the > spatial_ref_sys > table associating an SRS ID with the PROJ.4 definition. > > eg (at proj.4 commandline): > > cs2cs +proj=latlong +datum=WGS84 +to +proj=geocent > -117 33 > -2430880.68 -4770871.97 3453958.64 > > Best regards, > -- > --------------------------------------- > +-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, > warmerdam@... > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | President OSGeo, http:// > osgeo.org > > Nicolas already mailed last week about geocentric support, and i think he wants the whole postgis to support geodetic coordinates, not only a geodetic projection system. That means, actually, a support of geometric operations on a ellipsoid, not a plan, (as it is done today AFAIK). For example, on a plan, two geometries placed at a -180 + 180 are far, on the ellipsoid, they are near. (another example with two objects the same latitude latitudes, with a fixed longitude, they are farther at low (near 0) latitudes and nearer at extreme latitudes, but in a plan, distance is constant). (as nicolas said last week, Oracle spatial implements that) Today, operations are done by geos, and i didn't found anything that shows the possibility to to do geometric operation in another space than a plan. If i'm wrong then it's a good news, because full geodetic support could be added very quickly (just have to specify type of space to geos), but i don't think it is the case, since performing operations on a ellipsoid is slower and more complex (depending on implementation, the algos are more complex, or the mathematical model is more complex, or both). I'd be happy to see that one day, GIS world is evolving very fast these days, and virtual globes may make people need that kind of features much more than with the classical 2D, projection based, viewer (even if continuous horizontal scrolling is not uncommon). But i would not be surprise that creating another implementation of basic geos algorithms would make it possible, it would be interesting to know how complex it would be, and if it could make all the others geos function work auto-magically (having to fix the whole geos code would be sad, long and painfull). This is for the geometric operations. There is also a problem with the RTree BBoxes, since the RTree relies on distance, and distance depends of calculation formulas, for the same data, a geodetic RTree would not be the same as the RTrees we currently use. Since it could not be simple as greater than a lower than operations on BBoxes corners, i don't know what would be the actual runtime cost, but i'm not optimistic. But i'm not an expert, i'm just curious to see what kind of problems it raises. This is a great feature and i'd like to see it, but i would not ask for something that implies too much work. Best Regards _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Paul Ramsey
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You are correct, the request was for geodetic support, not geocentric
support, and that support requires: - Operations on a spher(oid) - Indexes for a spher(oid) Neither of which are currently available (except for distance_sphere and distance_spheriod). It's fiddly stuff, and implies a fair amount of duplication with the existing cartesian support, that is, touching a lot of the code base, so it's not a small project. P ValiSystem wrote: > But i would not be surprise that creating another implementation of > basic geos algorithms would make it possible, it would be interesting to > know how complex it would be, and if it could make all the others geos > function work auto-magically (having to fix the whole geos code would be > sad, long and painfull). > > This is for the geometric operations. There is also a problem with the > RTree BBoxes, since the RTree relies on distance, and distance depends > of calculation formulas, for the same data, a geodetic RTree would not > be the same as the RTrees we currently use. Since it could not be > simple as greater than a lower than operations on BBoxes corners, i > don't know what would be the actual runtime cost, but i'm not optimistic. > > But i'm not an expert, i'm just curious to see what kind of problems it > raises. This is a great feature and i'd like to see it, but i would not > ask for something that implies too much work. -- Paul Ramsey Refractions Research http://www.refractions.net pramsey@... Phone: 250-383-3022 Cell: 250-885-0632 _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Nicolas Ribot
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> Nicolas,
> > I believe PROJ.4 already supports geocentric coordinate systems, so in > theory it should be as simple as adding a new entry in the spatial_ref_sys > table associating an SRS ID with the PROJ.4 definition. > > eg (at proj.4 commandline): > > cs2cs +proj=latlong +datum=WGS84 +to +proj=geocent > -117 33 > -2430880.68 -4770871.97 3453958.64 > > Best regards, > -- thank you. As Vali mentionned, a true geocentric support 'a la Oracle' would be nice. nico _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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Re: PostGIS 2.0 Wishlist
by Paul Ramsey
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Nicolas Ribot wrote:
> As Vali mentionned, a true geocentric support 'a la Oracle' would be nice. FYI, the term you want is "geodetic". "Geocentric" coordinates are triples, (x, y, z) measured in 3-space relative to the center of the earth. "Geodetic" coordinates are angular coordinates (lat, lon) measured relative to a reference origin angle (equator, greenwich) or (equator, paris) or ... P. -- Paul Ramsey Refractions Research http://www.refractions.net pramsey@... Phone: 250-383-3022 Cell: 250-885-0632 _______________________________________________ postgis-users mailing list postgis-users@... http://postgis.refractions.net/mailman/listinfo/postgis-users |
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