[postgis-users] srid

Bob Pawley rjpawley at shaw.ca
Tue May 27 07:41:08 PDT 2008


Hi Regina

You are right in thinking that the Postgis model can be useful in apps other 
that geographic.

My little project is best summed up by the term Data Driven Design. 
Basically, I have created a prototype design model for designing industrial 
plants (Oil and Gas, Pulp and Paper etc.) in PostgreSQL. For the functions 
so far included, it works quite well.

The principal behind DDD is the wealth of information hidden within basic 
data and the fact that there are fundamental scientific laws and wide 
ranging industry standards that can be employed to drive information, which 
then drives further information until the design is complete.

What I am now doing is attempting to use the data to drive the graphic 
representation of the relational datastream. It wouldn't do to have a data 
system, which will soon become self organizing and self generating, then 
expect the user to manually draw the graphics one line, one circle and one 
peice of text at a time.

If you're interested in learning more about my version of Data Driven design 
check out my website www.automatingdesign.com.

I can easily see this technology being exploited for other industries such 
as architectural and the facility design for the manufacturing industry and, 
quite possibly, many others.

Bob



----- Original Message ----- 
From: "Paragon Corporation" <lr at pcorp.us>
To: "'PostGIS Users Discussion'" <postgis-users at postgis.refractions.net>
Sent: Monday, May 26, 2008 8:08 PM
Subject: RE: [postgis-users] srid


> Bob,
>
> I find it very interesting what you are trying to do.  I've always thought
> that the whole spatial database model can be usefully applied to other
> domains besides geography.  It is nice to see someone trying to do that.
>
> As far as ST_Transform goes,  still not quite clear how it plays into your
> problem.  To be honest - I haven't really delved into the guts of what
> assumptions proj4 makes about geometry models except that it was founded 
> on
> dealing with geography data.
>
> The whole Transformation infrastructure of PostGIS is based on proj4 and
> really the proj4text in the spatial_ref_sys as far as I know is all that 
> is
> used by the PostGIS ST_Transform (srid for lookup).
>
> I would imagine to expand its use for other domains in a meaningful way we
> would probably have to replace the field proj4text in spatial_ref_sys 
> tables
>
> with  - projmodeltext,  projmodel
>
> Where projmodel would define a library used for doing the spatial 
> transforms
> (in current case - they would all be filled in with 'proj4') , 
> projmodeltext
> would be the transformation params that the model needs
> and then any spatial reference systems based on the same function model 
> can
> be transformed in between each other.
>
> Note: PostGIS actually deviates from the standard OGC spatial_ref_sys
> structure in that in the plain vanilla OGC Spatial_ref_sys,  proj4text 
> field
> doesn't exist.
>
>
> Just my 2 cents,
> Regina
>
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Bob
> Pawley
> Sent: Monday, May 26, 2008 9:34 PM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] srid
>
> That is what I am attempting.
>
> I know of Visio. My thought of using Postgis is to, if possible, use the
> functions that Postgis provides. In the very long range I was also
> considering the 3D aspect of Postgis.
>
> Your suggestion of using "boxes", presumably to provide reference points 
> is
> my backup method, if ST_Transform isn't applicable.
>
> I would still like to consider ST_Transform as it appears to be a more
> flexible approach.
>
> Bob
>
>
> ----- Original Message -----
> From: "Chris Hermansen" <chris.hermansen at timberline.ca>
> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
> Sent: Monday, May 26, 2008 6:05 PM
> Subject: Re: [postgis-users] srid
>
>
>> Or, in another direction... Bob, if your "geometrical data" is meant to
>> be something like a "data flow diagram" or a "process diagram", you can
>> surely do that with PostGIS.
>>
>> Doubtless you must be aware of tools like Visio (in Windoze) or Dia (in
>> Linux or Windoze) that are made for drawing diagrams like "data flow",
>> but nevertheless you've decided to put your data into PostGIS instead.
>>
>> Then you probably want to make some "boxes" in your process diagram
>> appear above, below, to the right of, or to the left of, other boxes.
>>
>> To do that, you would need to define some kind of partial order on the
>> boxes (this box is to the right of that box, etc).  This sounds like a
>> topological sort to me.
>>
>> Presumably you could turn that topological ordering into some set of
>> offsets that could be applied to compute coordinates of each box.
>>
>> is that where you're trying to end up?
>>
>> Andy Anderson wrote:
>>> On May 26, 2008, at 3:06 PM, Bob Pawley wrote:
>>>
>>>> However, I attempting to interpret functions made for geographic data
>>>> to use with geometric data.
>>>>
>>>> I have PostgreSQL tables which represent engineering processes.
>>>>
>>>> I want to display that data in a graphical form - hopefully using
>>>> Postgis - - - if I can translate the functions (or the Postgis
>>>> concept) into a form that I can use.
>>>
>>> Hmmm... if all you want to do is display X-Y data, I would suggest
>>> using geographic coordinates, e.g. SRID = 4326 (WGS84 datum), which
>>> most programs will display by default with X and Y rectilinear.
>>>
>>> However, you earlier said you wanted to use ST_Transform(geometry,
>>> integer), which implies you want to switch between different 
>>> geographies.
>>>
>>> So it sounds like you need to pick a particular projection for your 
>>> work.
>>>
>>> Is your geography spherical or spheroidal? If so, you might want to
>>> define your own datum. If not, you'll need to use a projection to a
>>> flat surface. What's more important, that it be conformal
>>> (equiangular) or equal area or that it preserve distance in one
>>> direction?
>>>
>>> -- Andy
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>>
>> -- 
>> Regards,
>>
>> Chris Hermansen         mailto:chris.hermansen at timberline.ca
>> tel+1.604.714.2878 . fax+1.604.733.0631 . mob+1.778.232.0644
>> Timberline Natural Resource Group . http://www.timberline.ca
>> 401 . 958 West 8th Avenue  . Vancouver BC . Canada . V5Z 1E5
>>
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