Re: [mapserver-users] colorramp and datarange on the fly?
Would be dead easy with postGIS ... Jan On 3-2-2010 12:12, Bart van den Eijnden wrote: Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] colorramp and datarange on the fly?
Hi Jan, can you elaborate on this approach? Using WKTRaster? Best regards, Bart On Feb 3, 2010, at 2:11 PM, Jan Hartmann wrote: Would be dead easy with postGIS ... Jan On 3-2-2010 12:12, Bart van den Eijnden wrote: Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] colorramp and datarange on the fly?
Hi Bart,
Not sure if this is what you mean, but you can always compute a variable
with the range you want. The following is inefficient, and not really
dead easy, but it works.
Say, in your PostGIS table tbl, your want to display the column val
in 10 colors, with [minx],[miny],[maxx],[maxy] as the current extent
values (e.g. from a template) and mysrid as the srid:
LABELITEM labelval
select round ( ((val::float - min) / (max - min)) * 10) as labelval
from (
select min(val) as min,max(val) as max
from tbl
where the_geom st_setsrid('BOX3D(' || [minx] || ' ' ||
[miny] || ',' || [maxx] || ' ' || [maxy] || ')'::box3d,mysrid)
) as foo1
, (
select val from tbl
) as foo2
;
Jan
On 3-2-2010 14:14, Bart van den Eijnden wrote:
Hi Jan,
can you elaborate on this approach? Using WKTRaster?
Best regards,
Bart
On Feb 3, 2010, at 2:11 PM, Jan Hartmann wrote:
Would be dead easy with postGIS ...
Jan
On 3-2-2010 12:12, Bart van den Eijnden wrote:
Hi list,
is it possible to have a colorramp in Mapserver based on the min and max value
in the current extent?
So instead of predefining the min and max in DATARANGE, have Mapserver use the
min and max value of the dataset in the current extent?
If not, would it be an easy change or a very complex one?
Best regards,
Bart___
mapserver-users mailing list
mapserver-users@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/mapserver-users
___
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mapserver-users@lists.osgeo.org
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RE: [mapserver-users] colorramp and datarange on the fly?
How big a change would depend on the implementation. The brute force approach where you simply loop through features once to compute ranges and then again to draw would be probably pretty straight forward and driver independent. Wouldn't be fast (but would be simple). Complexity would be added as you try and boost performance by: - allowing drivers to compute stats in their own way (e.g. add to the layer API something like msLayerGetStats(...)) - caching geometries from a first pass through the shapes for the second Steve BTW The color ramp support needs to be cleaned up first. I think we scared the originator of that code away when an RFC was originally put together. -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Bart van den Eijnden Sent: Wednesday, February 03, 2010 5:12 AM To: mapserver-users@lists.osgeo.org Subject: [mapserver-users] colorramp and datarange on the fly? Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly?
If you allow two passes, you can have all sorts of summarized values in the template, to be used in the second pass, like Bart's actual extent used for coloring. Doesn't look to difficult to implement to me, as long as the two passes only get called when really necessary. I'm not sure if performance is an issue for MapServer itself: if you really want high performance, you should use the underlying format or database directly. Jan On 3-2-2010 17:02, Lime, Steve D (DNR) wrote: How big a change would depend on the implementation. The brute force approach where you simply loop through features once to compute ranges and then again to draw would be probably pretty straight forward and driver independent. Wouldn't be fast (but would be simple). Complexity would be added as you try and boost performance by: - allowing drivers to compute stats in their own way (e.g. add to the layer API something like msLayerGetStats(...)) - caching geometries from a first pass through the shapes for the second Steve BTW The color ramp support needs to be cleaned up first. I think we scared the originator of that code away when an RFC was originally put together. -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Bart van den Eijnden Sent: Wednesday, February 03, 2010 5:12 AM To: mapserver-users@lists.osgeo.org Subject: [mapserver-users] colorramp and datarange on the fly? Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly?
Right, I think there are two use cases: 1) data exploration - can be slower but needs flexibility 2) production serving - needs to be fast, and probably limits flexibility to some predefined models I think that there is also another angle to this, which is how the summary data is computed for example: 1) min/max/average/std 2) statistical analysis 3) binning into some number of classes 4) removing outliers so the results are not skewed by them 5) etc There are a lot of ways the people might need to summarize they data. If the data is in a database, then you can add all the analysis, slicing and dicing to the database and the rendering to mapserver. So, I think that it would be nice to be able to read some metadata about a layer and then use that for building the display using something like colorramp and datarange. We might want to look at ways that we could establish in mapserver for fetching the metadata about a layer. For example: 1) define the metadata in the METADATA object 2) define a .met file for a shapefile or tileindex that contained the metadata for that layer 3) define a separate SQL query that could be used to fetch the metadata for the layer 4) something similar for other layer providers. 5) scan the data in two passes to compute some simple metadata Thoughts? -Steve W Jan Hartmann wrote: If you allow two passes, you can have all sorts of summarized values in the template, to be used in the second pass, like Bart's actual extent used for coloring. Doesn't look to difficult to implement to me, as long as the two passes only get called when really necessary. I'm not sure if performance is an issue for MapServer itself: if you really want high performance, you should use the underlying format or database directly. Jan On 3-2-2010 17:02, Lime, Steve D (DNR) wrote: How big a change would depend on the implementation. The brute force approach where you simply loop through features once to compute ranges and then again to draw would be probably pretty straight forward and driver independent. Wouldn't be fast (but would be simple). Complexity would be added as you try and boost performance by: - allowing drivers to compute stats in their own way (e.g. add to the layer API something like msLayerGetStats(...)) - caching geometries from a first pass through the shapes for the second Steve BTW The color ramp support needs to be cleaned up first. I think we scared the originator of that code away when an RFC was originally put together. -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Bart van den Eijnden Sent: Wednesday, February 03, 2010 5:12 AM To: mapserver-users@lists.osgeo.org Subject: [mapserver-users] colorramp and datarange on the fly? Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly?
To add a little more to this... What I have done in the past for thematic maps is to do the analysis in the database and to bin the data into a new column or columns for each analysis. Then in my mapfile, I can select the column that I want to display. This made it easy to get fast maps because mapserver only had to render based on a simple value 1-n based on the number of bins I computed. I have also create a stored procedure in the past that I could pass in the number of bins and the type of analysis, and it would then compute the binned values on the fly. I found that there was a lot of flexibility doing this in postgresql and have mapserver generate the maps. This would also be a good way to prototype up the various analysis that you might want to explore. The one big missing piece to doing this is that there is not easy way to dynamically change the number of classes (bins) that are being generated in mapserver and assign them colors, which the colorramp and datarange would help with especially if there were a way to get those values dynamically from the data source. -Steve W Stephen Woodbridge wrote: Right, I think there are two use cases: 1) data exploration - can be slower but needs flexibility 2) production serving - needs to be fast, and probably limits flexibility to some predefined models I think that there is also another angle to this, which is how the summary data is computed for example: 1) min/max/average/std 2) statistical analysis 3) binning into some number of classes 4) removing outliers so the results are not skewed by them 5) etc There are a lot of ways the people might need to summarize they data. If the data is in a database, then you can add all the analysis, slicing and dicing to the database and the rendering to mapserver. So, I think that it would be nice to be able to read some metadata about a layer and then use that for building the display using something like colorramp and datarange. We might want to look at ways that we could establish in mapserver for fetching the metadata about a layer. For example: 1) define the metadata in the METADATA object 2) define a .met file for a shapefile or tileindex that contained the metadata for that layer 3) define a separate SQL query that could be used to fetch the metadata for the layer 4) something similar for other layer providers. 5) scan the data in two passes to compute some simple metadata Thoughts? -Steve W Jan Hartmann wrote: If you allow two passes, you can have all sorts of summarized values in the template, to be used in the second pass, like Bart's actual extent used for coloring. Doesn't look to difficult to implement to me, as long as the two passes only get called when really necessary. I'm not sure if performance is an issue for MapServer itself: if you really want high performance, you should use the underlying format or database directly. Jan On 3-2-2010 17:02, Lime, Steve D (DNR) wrote: How big a change would depend on the implementation. The brute force approach where you simply loop through features once to compute ranges and then again to draw would be probably pretty straight forward and driver independent. Wouldn't be fast (but would be simple). Complexity would be added as you try and boost performance by: - allowing drivers to compute stats in their own way (e.g. add to the layer API something like msLayerGetStats(...)) - caching geometries from a first pass through the shapes for the second Steve BTW The color ramp support needs to be cleaned up first. I think we scared the originator of that code away when an RFC was originally put together. -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Bart van den Eijnden Sent: Wednesday, February 03, 2010 5:12 AM To: mapserver-users@lists.osgeo.org Subject: [mapserver-users] colorramp and datarange on the fly? Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev
RE: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly?
At one point I toyed with the idea of supporting a .stats file for a layer and supplying a routine (command-line) that would populate it. The file would contain data like you're talking about. Doesn't help with the on-the-fly needs Bart was articulating. Steve -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Stephen Woodbridge Sent: Wednesday, February 03, 2010 10:39 AM To: Jan Hartmann Cc: Lime, Steve D (DNR); MapServer Dev Mailing List; mapserver-users@lists.osgeo.org Subject: Re: [mapserver-dev] RE: [mapserver-users] colorramp and datarange on the fly? Right, I think there are two use cases: 1) data exploration - can be slower but needs flexibility 2) production serving - needs to be fast, and probably limits flexibility to some predefined models I think that there is also another angle to this, which is how the summary data is computed for example: 1) min/max/average/std 2) statistical analysis 3) binning into some number of classes 4) removing outliers so the results are not skewed by them 5) etc There are a lot of ways the people might need to summarize they data. If the data is in a database, then you can add all the analysis, slicing and dicing to the database and the rendering to mapserver. So, I think that it would be nice to be able to read some metadata about a layer and then use that for building the display using something like colorramp and datarange. We might want to look at ways that we could establish in mapserver for fetching the metadata about a layer. For example: 1) define the metadata in the METADATA object 2) define a .met file for a shapefile or tileindex that contained the metadata for that layer 3) define a separate SQL query that could be used to fetch the metadata for the layer 4) something similar for other layer providers. 5) scan the data in two passes to compute some simple metadata Thoughts? -Steve W Jan Hartmann wrote: If you allow two passes, you can have all sorts of summarized values in the template, to be used in the second pass, like Bart's actual extent used for coloring. Doesn't look to difficult to implement to me, as long as the two passes only get called when really necessary. I'm not sure if performance is an issue for MapServer itself: if you really want high performance, you should use the underlying format or database directly. Jan On 3-2-2010 17:02, Lime, Steve D (DNR) wrote: How big a change would depend on the implementation. The brute force approach where you simply loop through features once to compute ranges and then again to draw would be probably pretty straight forward and driver independent. Wouldn't be fast (but would be simple). Complexity would be added as you try and boost performance by: - allowing drivers to compute stats in their own way (e.g. add to the layer API something like msLayerGetStats(...)) - caching geometries from a first pass through the shapes for the second Steve BTW The color ramp support needs to be cleaned up first. I think we scared the originator of that code away when an RFC was originally put together. -Original Message- From: mapserver-users-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Bart van den Eijnden Sent: Wednesday, February 03, 2010 5:12 AM To: mapserver-users@lists.osgeo.org Subject: [mapserver-users] colorramp and datarange on the fly? Hi list, is it possible to have a colorramp in Mapserver based on the min and max value in the current extent? So instead of predefining the min and max in DATARANGE, have Mapserver use the min and max value of the dataset in the current extent? If not, would it be an easy change or a very complex one? Best regards, Bart___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-dev mailing list mapserver-...@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-dev ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
