[jump-users] Better Performence for point data

Rahkonen Jukka Jukka.Rahkonen at mmmtike.fi
Thu Oct 4 06:25:01 PDT 2007


Hi Larry,
 
Perhaps Geonames database http://www.geonames.org/export/ has enough points for testing.
 
 
-Jukka-


________________________________

	Lähettäjä: jump-users-bounces at lists.jump-project.org [mailto:jump-users-bounces at lists.jump-project.org] Puolesta Larry Becker
	Lähetetty: 4. lokakuuta 2007 16:17
	Vastaanottaja: JUMP Users Discussion
	Aihe: Re: [jump-users] Better Performence for point data
	
	
	I'm going to start investigating the point performance problem as soon as I get some test data.  I have been trying to locate a large point dataset on the web, but no luck.  Perhaps the best approach might be to add a new item to the Generate menu, "Random Points". 
	
	@Arnd: One thing that people often forget about JUMP is that rendering is a background  process.  You don't have to wait for it to finish to start the next operation.  
	
	What kind of terrain maps are you generating?  Are you generating contour lines from a grid of points?  You mentioned deleting selected points being impossibly slow.  I don't see why this should be so.  If I can duplicate the problem, it should be an easy fix. 
	
	regards,
	Larry
	
	
	On 10/2/07, Larry Becker <becker.larry at gmail.com> wrote: 

		HI Arnd,
		
		  Would it be helpful to work around the problem by saving the points as a shapefile and using a utility like shp2tile to break the point data up into multiple files?
		
		see: http://imaptools.com/download-software.html
		
		regards,
		Larry 
		
		
		
		On 10/2/07, Arnd Kielhorn < a.kielhorn at gmx.de > wrote: 

			Hello Paul,
			
			thank You for the tip with the z-value, but how I can use it as a 
			z-value on the point itself?
			
			The file fomrat is txt, csv (from PIROL CSV-Format) like following example
			$Rechts    Hoch    heigh
			$grad    grad    m
			$double    double    double
			3434000.00    5800000.00     93.78
			3434001.00    5800000.00    93.84
			...   ...   ...
			
			or the ESRI ascii grid format asc (reading plugin from SIGLE).
			The most files I got have 1 million points and such csv files have about
			30 MB. 
			In my start file for OJ I got 768 MB, because I have 1 GB RAM.
			
			Kindly regards
			Arnd
			
			
			Paul Austin schrieb:
			> Arnd,
			>
			> What file format are you using?
			>
			> As JUMP loads the whole file into memory I would recommend setting the 
			> heap size on the JAVA VM to be -Xmx512M if you are dealing with large
			> datasets.
			>
			> You mentioned that the height is an attribute on the feature, if you use
			> the height as a z-value on the point itself there will be some memory 
			> savings.
			>
			> Paul
			>
			> Arnd Kielhorn wrote:
			>
			>> Hello Larry,
			>>
			>> as in the further discussion just named the main problema are (for
			>> example I just have to work with point layers with only a heigh 
			>> attribute but with 1 million points; but also e.g. 300,000 points are
			>> enough):
			>> - (re)drawing of the points
			>> - strongly restricted or impossible operation (e.g. deleting some 
			>> points/vertices after marking them; e.g. copying hundreds or a few
			>> thousand in a new layer to have layer with lesser points)
			>> Very often OJ hangs on and I have to restart it.
			>> I use such point layers for creating a digital terrain maps. 
			>>
			>> Kindly regards
			>> Arnd
			>>
			>> Larry Becker schrieb:
			>>
			>>> Hi Arnd,
			>>>
			>>>   I haven't worked with large point datasets much.  What it is 
			>>> exactly that is slow?  Is it redraw time?  Or perhaps the particular
			>>> operation that you are doing?
			>>>
			>>>   I know that point layers do not benefit from the recent decimation 
			>>> optimization, so they take longer to draw than equivalent polygons
			>>> and polyline layers.  I think Michaël tried a point decimation
			>>> optimization, but wasn't satisfied with the results. 
			>>>
			>>> regards,
			>>> Larry Becker
			>>>
			>>> On 10/1/07, *Stefan Steiniger* < sstein at geo.uzh.ch <mailto:sstein at geo.uzh.ch> 
			>>> <mailto: sstein at geo.uzh.ch>> wrote:
			>>>
			>>>     mhm
			>>>     from my point of view it is both OJ and JRE. It would be probably 
			>>>     better 
			>>>     when the points are stored and processes in a database.
			>>>
			>>>     stefan
			>>>
			>>>     Arnd Kielhorn schrieb:
			>>>     > Hello,
			>>>     > 
			>>>     > yes I know, first of all OJ is a GIS for vector data. But the
			>>>     > functionality is also very good for point datasets. But working
			>>> with
			>>>     > great point datasets (more 500,000 points) bring problems with the 
			>>>     > memory and the garbage collector works not satisfied. Every
			>>>     command take
			>>>     > a lot of time or could not carried out. (CPU P4 2.4 GHz, 1 GB RAM)
			>>>     > Is it only a thing of the JRE or also from OJ? 
			>>>     > So, it is useful to know if there is a chance to increase the
			>>>     > performence of OJ in this case and what could be the possible
			>>>     milestones
			>>>     > to reach this aim? 
			>>>     > I am very eager to read everyones opion.
			>>>     >
			>>>     > Kindly regards
			>>>     > Arnd
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