[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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