Re: [postgis-users] [postgis-devel] GSOC Postgis Project

[Simon Greener]

I would support this and am prepared to be a beta tester.
Simon
On Sat, 10 Mar 2018 16:38:29 +1100, P Kishor  wrote:


I normally despise and refrain from the +1 posts. But heck, this is one venture 
I want to emphatically +1. Good luck Rahul, it will indeed be very nice to have 
a spatial viewer integrated into PgAdmin

Puneet


On Mar 10, 2018, at 10:34 AM, Regina Obe  wrote:

Rahul,

Not sure if Victoria hangs out on dev or not.   I've cc'd her and also PostGIS 
Users of your interest.
I also cc'd Dave in case he has any words of wisdom to share.  (Dave sorry for 
the call out but thought you might be interested in this since it's desired it 
could be integrated in pgAdmin4 J ).
Looks like you have made progress already.  I'm very excited at the thought of 
having a spatial viewer in pgAdmin4.

Thanks,
Regina

From: postgis-devel [mailto:postgis-devel-boun...@lists.osgeo.org] On Behalf Of 
Rahul Soshte
Sent: Friday, March 09, 2018 3:09 PM
To: postgis-de...@lists.osgeo.org; disc...@lists.osgeo.org
Subject: [postgis-devel] GSOC Postgis Project

Hi,

I am Rahul Soshte,a 3rd Year Computer Engineering Student from Mumbai 
University.

I quite liked the idea of a Spatial Query viewer for pgadmin4 which would be a 
quick handy tool for viewing the output of the geospatial queries which is 
mentioned here.

I am willing to contribute to this organization by Leveraging my efforts for 
this GSOC project.

I have solved the 2 Tasks mentioned in the link which were the tasks for 
potential GSOC students and the output and code of both the tasks are attached 
hereby.

Code:https://github.com/rahul-soshte/gsoctaskspostgis

For the Task 2->I have used OpenLayers and displayed a JSON layer by 
procuring data from here.

https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_month.geojson

which is data about earthquakes in the past month over the world.

For the next step I will be setting up my development environment for the 
project.

Regards,
Rahul Soshte
(Here's a 'brief' and 'plain' description of myself)


…


--
Puneet Kishor
Just Another Creative Commoner
http://punkish.org/About

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Re: [postgis-users] [postgis-devel] GSOC Postgis Project

[P Kishor]

I normally despise and refrain from the +1 posts. But heck, this is one venture 
I want to emphatically +1. Good luck Rahul, it will indeed be very nice to have 
a spatial viewer integrated into PgAdmin

Puneet

> On Mar 10, 2018, at 10:34 AM, Regina Obe  wrote:
> 
> Rahul,
>  
> Not sure if Victoria hangs out on dev or not.   I've cc'd her and also 
> PostGIS Users of your interest.
> I also cc'd Dave in case he has any words of wisdom to share.  (Dave sorry 
> for the call out but thought you might be interested in this since it's 
> desired it could be integrated in pgAdmin4 J ).
> Looks like you have made progress already.  I'm very excited at the thought 
> of having a spatial viewer in pgAdmin4.
>  
> Thanks,
> Regina
>  
> From: postgis-devel [mailto:postgis-devel-boun...@lists.osgeo.org] On Behalf 
> Of Rahul Soshte
> Sent: Friday, March 09, 2018 3:09 PM
> To: postgis-de...@lists.osgeo.org; disc...@lists.osgeo.org
> Subject: [postgis-devel] GSOC Postgis Project
>  
> Hi,
> 
> I am Rahul Soshte,a 3rd Year Computer Engineering Student from Mumbai 
> University.
> 
> I quite liked the idea of a Spatial Query viewer for pgadmin4 which would be 
> a quick handy tool for viewing the output of the geospatial queries which is 
> mentioned here.
> 
> I am willing to contribute to this organization by Leveraging my efforts for 
> this GSOC project.
> 
> I have solved the 2 Tasks mentioned in the link which were the tasks for 
> potential GSOC students and the output and code of both the tasks are 
> attached hereby.
> 
> Code:https://github.com/rahul-soshte/gsoctaskspostgis
>  
> For the Task 2->I have used OpenLayers and displayed a JSON layer by 
> procuring data from here.
> 
> https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_month.geojson
> 
> which is data about earthquakes in the past month over the world.
>  
> For the next step I will be setting up my development environment for the 
> project.
> 
> Regards,
> Rahul Soshte
> (Here's a 'brief' and 'plain' description of myself)
> 
>  
> …

--
Puneet Kishor
Just Another Creative Commoner
http://punkish.org/About

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Re: [postgis-users] [postgis-devel] GSOC Postgis Project

[Regina Obe]

Rahul,

 

Not sure if Victoria hangs out on dev or not.   I've cc'd her and also PostGIS 
Users of your interest.

I also cc'd Dave in case he has any words of wisdom to share.  (Dave sorry for 
the call out but thought you might be interested in this since it's desired it 
could be integrated in pgAdmin4 :) ).

Looks like you have made progress already.  I'm very excited at the thought of 
having a spatial viewer in pgAdmin4.

 

Thanks,

Regina

 

From: postgis-devel [mailto:postgis-devel-boun...@lists.osgeo.org] On Behalf Of 
Rahul Soshte
Sent: Friday, March 09, 2018 3:09 PM
To: postgis-de...@lists.osgeo.org; disc...@lists.osgeo.org
Subject: [postgis-devel] GSOC Postgis Project

 

Hi,


I am Rahul Soshte,a 3rd Year Computer Engineering Student from Mumbai 
University.


I quite liked the idea of a Spatial Query viewer for pgadmin4 which would be a 
quick handy tool for viewing the output of the geospatial queries which is 
mentioned here  .


I am willing to contribute to this organization by Leveraging my efforts for 
this GSOC project.


I have solved the 2 Tasks mentioned in the link 
  which were the 
tasks for potential GSOC students and the output and code of both the tasks are 
attached hereby.

Code:https://github.com/rahul-soshte/gsoctaskspostgis

 

For the Task 2->I have used OpenLayers and displayed a JSON layer by 
procuring data from here.

https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_month.geojson

which is data about earthquakes in the past month over the world.

 

For the next step I will be setting up my development environment for the 
project.

Regards,

Rahul Soshte
(Here's a 'brief' and 'plain' description of myself 
 )

 

 

 

 

 

 

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Re: [postgis-users] Aggregating rasters by adding and other confusions

[Regina Obe]

David,

 

I took a cursory glance at the union code we have in place.

What it seems to do is two passes

 

1 pass does an ST_Union using 'COUNT'  (so in your case you'd get numbers 
between 0 and 3, 0 being no rasters considered having any data)

2nd pass does an ST_Union using 'SUM'  

And returns a new raster  where each pixel is  SUM/COUNT

 

Basic code is here:

 

http://postgis.net/docs/doxygen/2.4/da/dde/rtpg__mapalgebra_8c_a1d94065e6cef5d5d61417b82b2cf4fb6.html#a1d94065e6cef5d5d61417b82b2cf4fb6

(note it only computes a value if the first band (which I presume to be the 
count band)  value > 0  and has no nodata value. )

I don't know why a count band would have a nodata value aside from when it's 0

 

What does COUNT return for you?  

 

Thanks,

Regina

 

From: postgis-users [mailto:postgis-users-boun...@lists.osgeo.org] On Behalf Of 
David M. Kaplan
Sent: Tuesday, March 06, 2018 10:29 AM
To: postgis-users@lists.osgeo.org
Subject: Re: [postgis-users] Aggregating rasters by adding and other confusions

 

Hi,

 

Yes, this does seem to be the solution. For completeness, the following did the 
same thing as my aggregate function:

 

SELECT ST_Union(rast,1,'SUM') FROM blah;

This includes replacing 0's with NULL's - ST_Union had the same behavior at my 
aggregate function. 

 

Can you explain this? For my sum, this isn't a big deal, but ST_Union(... 
'MEAN') seems to be treating 0's at NULL values, thereby removing them from the 
mean calculation:

 

db=# SELECT (ST_SummaryStats(ST_Union(rast,1,'SUM'))).sum FROM blah; sum  
--
 2792
(1 row)
 
db=# SELECT (ST_SummaryStats(ST_Union(rast,1,'MEAN'))).sum FROM blah;
 sum  
--
 1346
(1 row)
 

The table "blah" has 3 rasters with no null values, so I would expect the sum 
of the mean to be 1/3 the sum of the sum, but clearly this is not the case.

 

I tried playing around with the no data value for my rasters to see if this 
would change things. It does change things, but not in any way I can explain:

 

fads=# SELECT 
(ST_SummaryStats(ST_Union(ST_SetBandNoDataValue(rast,1,0),1,'MEAN'))).sum FROM 
blah;
 sum  
--
 2025
(1 row)
 
fads=# SELECT 
(ST_SummaryStats(ST_Union(ST_SetBandNoDataValue(rast,1,-999),1,'MEAN'))).sum 
FROM blah;
 sum  
--
 2025
(1 row)
 

Setting the no data value has no effect on the sum of the sum.

 

Does any of this make sense?

 

Thanks,

David

 

 

On Mon, 2018-03-05 at 12:00 -0800, postgis-users-requ...@lists.osgeo.org 
  wrote:

Date: Mon, 5 Mar 2018 12:05:40 -0500
From: "Regina Obe"  >
To: "'PostGIS Users Discussion'"  >
Subject: Re: [postgis-users] Aggregating rasters by adding and other
confusions
Message-ID: <001f01d3b4a4$30d1fa20$9275ee60$@pcorp.us 
 >
Content-Type: text/plain; charset="utf-8"
 
I think what you are looking for is ST_Union (.. SUM)  note this has union 
types – FIRST, MIN, MAX, COUNT, SUM, MEAN, RANGE
 
 
 
http://postgis.net/docs/manual-2.4/RT_ST_Union.html
 
 
 
 
 
 
 
From: postgis-users [mailto:postgis-users-boun...@lists.osgeo.org] On Behalf Of 
David M. Kaplan
Sent: Monday, March 05, 2018 10:03 AM
To: postgis-users@lists.osgeo.org  
Subject: [postgis-users] Aggregating rasters by adding and other confusions
 
 
 
Hi,
 
 
 
I have recently started working with the postgis raster functionality. In 
general, I have found this really useful and have been able to do some neat 
things fairly simply with this raster functionality. Nevertheless, there are a 
few basic things that I am confused about and I was hoping someone could give 
me a hand.
 
 
 
(1) First of all, I have a table with a bunch of rasters that have the same 
extent, alignment, scale, etc. and I want to aggregate them together into a 
single raster using pixel-by-pixel addition. It seems like there should be a 
function to do this, but I can't find one. Is there an aggregate 
"ST_MapAlgebra" function? 
 
 
 
Given that I couldn't find one, I defined an aggregate function as follows:
 
 
 
CREATE OR REPLACE FUNCTION AddRasters(r1 raster, r2 raster)
   RETURNS raster AS
$BODY$
SELECT ST_MapAlgebra($1,$2,'[rast1]+[rast2]');
$BODY$ LANGUAGE 'sql' IMMUTABLE STRICT;
 
CREATE AGGREGATE sum (raster)
(
sfunc = AddRasters,
stype = raster
);
 
 
(2) This seems to work, but it has the unexpected behavior that it replaces 0 
values with NULL. In my case, this is fine, but I am wondering why it does 
this? I can't find anything that indicates that it should be replacing zeros 
with NULL. Here is the metadata associated with one of my rasters (the others 
are similar):
 
 
 
# SELECT ST_BandMetadata(rast), ST_Metadata(rast), ST_SummaryStats(rast) FROM 
blah;
-[ RECORD 1 ]---+---
st_bandmetadata | (16BUI,,f,)

Re: [postgis-users] free tools for spatial data mining

[Sandro Santilli]

On Thu, Mar 08, 2018 at 10:34:14AM -0500, isla...@infomed.sld.cu wrote:
> Hello, are there free tools on the web to carry out spatial data mining
> processes?

Plenty. Can you be more specific about what you need ?
Why are you asking on PostGIS mailing list rather than in a
more generic one ? May I suggest you take a look at
https://www.osgeo.org for a broader view ?

--strk;
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