Simplifying the question:
How could I have raster data (GeoTiff), with daily frequency, and
portray the result of basic operation like sum, min, max, given a time
period ???
Am I forced to put the data inside PostGis ???? If not, how to perform
calculations over data in a file structure ????
Thanks in advance
-------- Original Message --------
Subject: Best approach for a classic time-series raster data problem.
Date: Fri, 18 Jul 2014 16:29:39 -0300
From: Elyser Estrada <[email protected]>
To: [email protected]
Hi there!
I have GeoServer 2.5.1 running with Postgre 9.3 and PostGis 2.1.
I would like to get your opinion about which is the best technical
approach to deal with this simple and classic situation:
I need to develop an application to show daily observations of some
variables and also allow some basic analysis (sum data for a time
period, min value for a period, max, mean, and so on..), portraying also
the results of those simple analyses.
I managed to put the daily data in GeoTiff format. Individual files size
between 1 and 3 megabytes and we have data since year 1970.
I already have this data published by means of an ImageMosaic store
indexed in Postgre and it works well using the "time" URL parameter. It
is clear that, as using the Postgre index, it seems there will not to be
a performance issue because of the daily frequency and the amount of
data. At the end GeoServer just locates the right image requested using
the index and access on disk directly.
The issue comes when trying to perform and map (via WMS) the result of
the simple aggregation or calculation operations.
After studying a bit about WPS it seems like it is not the must adequate
solution, it seems to be a too big hammer to hit a simple problem. Also
I would have to develop new processes and publish them in my GeoServer
installation to be used later. I reinforced that thought after watching
the Andrea Aime's presentation "Processing Data In GeoServer With WPS
And SQL Views".
So, as far, the best approach seems to be:
- To import all the raster data into PosgreSQL, this way enabling the
use of the potent PostGis functions to perform calculations.
- To create SQL View layers on GeoServer for each analysis operation
(one View retrieving added data, another minimal data, and so on).
- To pass parameters like "initialDate" and "finalDate" to the query in
the URL request, supported by respective date columns added to the image
data tables.
Then here go my worries and doubts about that approach:
- Due to the necessity to perform simple analyses over the data, and the
possibility to define a big time period to calculate: I must put the
data in the database and discard the system file approach, this way
getting the power of Postgre+PostGis. Right????
- I could use Image Mosaic JDBC GeoServer stores to support layers with
data in the database. But due to the fact that the Image Mosaic JDBC
extension does not support the use of the “time” parameter, I would have
to implement that mechanism by means of the SQL Views parameters. Right ????
- Must I use the pyramid and tiles approach to store my data in the
database, even when I expect not having files bigger than 3 mb ????
Nevertheless I think I could create at least one pyramid.
- Which plugin must I use for storing my data: Postgis Raster Plugin or
Image Mosaic JDBC ????
- Any suggestion about a more efficient approach to attack this classic
case ?????
Thanks in advance
Elyser
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