Re: Image Server, Shape Layers and Image bounds problem

Hi Paul,

Thanks for looking into this, it really helps. I'll check into this
before the next release, too.

- Don

On Tuesday, April 9, 2002, at 09:34 PM, Paul Chisholm wrote:

> Hi Don,
>
> thanks for the reply, it has helped me further investigate the problem.
> The -Ddebug.imageserver did not throw any light on the subject
> but -Ddebug.shape did.
>
> My chunk of code that generates the image is
>
> System.out.println(centre.toString() + "\nScale=" + scale +
> "\nWidth=" + width + "\nHeight="+ height);
> Mercator proj = new Mercator(centre, scale, width, height);
> server.setLayers(layers);
> byte[] bytes = server.getMapImage(proj);
>
> I added a trace statement to print the projection parameters. Here is a
> segment of the trace file.
> *******************************************************
> Request 1
> ---------
> LatLonPoint[lat=-30.0,lon=145.0]
> Scale=1.2E8
> Width=240
> Height=160
>
> OpenMap|ShapeLayer.ShapeWorker.construct(): getting graphics...
> ShapeLayer.computeGraphics(): Dateline is on screen
> OpenMap|ShapeLayer.ShapeWorker.construct(): fetched 70 graphics in 0.07
> seconds
> ShapeLayer.paint(): 70 omg shadow=0,0
> ShapeLayer.paint(): done
>
> Request 2
> ---------
> LatLonPoint[lat=-28.0,lon=135.0]
> Scale=1.2E7
> Width=480
> Height=400
>
> Land|ShapeLayer.ShapeWorker.construct(): getting graphics...
> Land|ShapeLayer.ShapeWorker.construct(): fetched 35 graphics in 0.05
> seconds
> ShapeLayer.paint(): 35 omg shadow=0,0
> ShapeLayer.paint(): done
>
> Request 3
> ---------
> LatLonPoint[lat=-30.0,lon=145.0]
> Scale=1.2E8
> Width=240
> Height=160
>
> ShapeLayer: projection not different, returning...
> OpenMap|ShapeLayer.ShapeWorker.construct(): getting graphics...
> ShapeLayer.computeGraphics(): Dateline is on screen
> OpenMap|ShapeLayer.ShapeWorker.construct(): fetched 70 graphics in 0.03
> seconds
>
> Request 4
> ---------
> LatLonPoint[lat=-30.0,lon=145.0]
> Scale=1.2E8
> Width=240
> Height=160
>
> OpenMap|ShapeLayer.ShapeWorker.construct(): getting graphics...
> ShapeLayer.computeGraphics(): Dateline is on screen
> OpenMap|ShapeLayer.ShapeWorker.construct(): fetched 70 graphics in 0.03
> seconds
> ShapeLayer.paint(): 70 omg shadow=0,0
> ShapeLayer.paint(): done
> *******************************************
>
> The interesting one is request 3. In particular the line
>
> ShapeLayer: projection not different, returning...
>
> It looks like the system thinks the projection is unchanged and doesnt
> regenerate the shape layer. However from the trace the projection must
> have
> changed since the parameters are different. This is the request in
> which the
> shape layer is missing from the image. I had a quick look at the code
> but I
> need to spend more time on it to make sense of it. As a test I created
> MyShapeLayer which over-rides projectionChanged in ShapeLayer with
>
> public void projectionChanged(ProjectionEvent ev) {
>
> Projection newProj = ev.getProjection();
> String newPID = newProj.getProjectionID();
> projection = newProj;
> projID = newPID;
>
> doPrepare();
> }
>
> I have just removed the test for the projection change. Using
> MyShapeLayer
> the problem disappears.
>
> Paul
>
> ----- Original Message -----
> From: "Don Dietrick" <dietrick@bbn.com>
> To: "Paul Chisholm" <paulch@bigpond.com>
> Cc: <openmap-users@bbn.com>
> Sent: Wednesday, April 10, 2002 12:54 AM
> Subject: Re: Image Server, Shape Layers and Image bounds problem
>
>
> Paul,
>
> When the shape layer is missing, is it even being asked for any
> graphics? You could set a -Ddebug.shape command line to see if it is
> getting pinged. Actually, you could use -Ddebug.imageserver for better
> messages about what the image server is doing with what layers.
>
> I haven't seen this behavior. The ImageServer should be calling the
> layer's ProjectionPainter method (renderDataForProjection()), so the
> layer shouldn't be reacting differently to any one projection over
> another - i.e. what you are expecting to happen should be happening.
>
> - Don
>
> On Tuesday, April 9, 2002, at 01:37 AM, Paul Chisholm wrote:
>
>> Hi,
>>
>> I have a server that uses OpenMap to generate JPEG files and it is
>> exhibiting some strange behaviour. The images are created via the
>> ImageServer class. Two different types of image are generated, one
>> essentially a large scale version of the other. Both consist of a shape
>> layer and a few other (non Shape) layers. What happens is:
>>
>> - request first image, ok
>> - request second image, shape layer missing
>> - request first image, shape layer missing
>> - request second image, shape layer missing
>> - request second image, ok
>> - request second image, ok
>> - request first image, shape layer missing
>> etc
>>
>> The pattern is that each time I change between maps the shape layer is
>> missing from the image. However, a subsequent request for the same map
>> includes the shape layer.
>>
>> I experimented with various parameters and eventually found that the
>> cause of the missing shape layer is due to the change in dimensions of
>> the image. That is, when there is a change to either <width> or
>> <height> in the following (wrt the previous request) the shape layer is
>> missing from the image (95% of the time).
>>
>> server.setLayers(<layers>);
>> Mercator proj = new Mercator(<centre>, <scale>, <width>,
>> <height>);
>> byte[] bytes = server.getMapImage(proj);
>>
>> Changing <centre>, <scale> or <layers> causes no problem.
>>
>> I am using OpenMap 4.4.2 on Windows NT 4 (SP6). Anyone know of any
>> reason why this behaviour occurs, or how I might be configuring
>> something incorrectly to induce the behaviour.
>>
>> Thanks,
>> Paul Chisholm
>>

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, BBN Technologies, dietrick@bbn.com
10 Moulton Street, Cambridge, MA 02138
617-873-3031 [fax]-2794
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>

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