Re: [OpenMap Users] OpenGL Panel considered?

From: Don Dietrick <>
Date: Fri, 26 May 2006 11:03:46 -0400

Hi Thomas,

You could do this, but the default OpenMap application isn't set up
for it. You could use OpenMap components to create textures for
overlay into 3d space objects, for instance. We've done this on some
internal projects here at BBN. Direct rendering is more complicated
because of the separation between the OpenMap Swing's lightweight
Java objects and the need for, say, OpenGL's need to deal with
heavyweight Java objects. I think there's been some progress on
lightweight-heavyweight integration, but it's been a while since I
looked into it and someone else can chime in on that.

On May 26, 2006, at 1:00 AM, Thomas Schar wrote:

> Hi,
> I was just wondering if there is any benefit to openmap makubg use
> of 3d hardware accel rendering? We are investigating the use of
> openmap in a near real-time update (ie. military situational
> awareness display) scenario and when combined with a single CADRG
> (RpfLayer), and a few (<20) OMGraphics, the rendering is too slow.
> < details >
> (talking between 2-10 secs to perform a pan and/or zoom -- this is
> on a Athlon64 2.x with 1 GB ram). The CADRG full data set is
> largish (450MB) but only a very small amount of the map is shown
> (say <1%). I'm not sure exactly how the CADRG is broken up into
> tile/cells, but it's an official NIMA dataset, so I'm hoping that
> it has been generated reasonably well.
> < /details >

Sounds like something else is going on. What's your OS and jdk
version? If you are using X Windows and running OpenMap remotely
with any transparency on the map, that will hurt performance a lot.
The GraticuleLayer has transparency set in it's lines by default, so
that's one thing that might be happening?

Each CADRG frame is broken into 36 (6x6) 256x256 pixel subframe
images, in terms of how it looks at the chart's native resolution.
When you zoom out, more frames are needed, obviously, and you might
want to change cache settings to see how that helps. The caches are
set to hold 4 frames and 40 subframes, and if you start blowing that
on pans, you'll start waiting for I/O. If you keep the map close to
the native scale of the images the response should be very quick.
There are property settings for these cache parameters, more
information is in the javadocs for the layer.

The size of the data set isn't that important wrt/performance, but
the number of RPF directories is. Also, using a data set available
via NFS will also be slower. You can use the palette of the layer to
turn the attributes on for a RpfLayer an see where the subframes
are. If you zoom to the native level of the displayed chart, you'll
see the other information of the subframe, like which frame it is
from, etc.

Also, do you have other layers on behind the CADRG? If you have a
Shape file political boundary on, it's still getting rendered even
though it's behind the CADRG, and that be just one more thing the cpu
has to prepare for rendering.

You can also think about marking layers as 'background', which will
place them in a special image buffer in the BufferedLayerMapBean (the
one used by default). This won't help for pans and zooms, but
performance of animation over a stable map will be greatly enhanced.
You can test this by adding an AnimationTester to the OpenMap
application (com.bbn.openmap.graphicLoader.AnimationTester to the
openmap.components property, along with a GraphicLoaderConnector).
If you bring up the palette that gets created for the
AnimationTester, you can add sprites and change timer settings to
make them wander around the map.

> Anyway, I was playing with ways of optimising the performance, when
> I just sort of wondered why 3d hardware accelearation isn't used
> more. Is this due to the immaturity of jogl/j3d/lwjgl libraries or
> because the hardware doesn't provide any benefit?

Java takes advantage of using hardware acceleration of the video card
when it can, but using the 3d acceleration is a different beast. You
have to define the stuff you want rendered in terms the hardware
understands, in 3d space, and compile those objects into the 3d
scene. All of the OMGraphic map objects that layers use render
themselves into the Graphics2D object of the parent component. Like
I mentioned above, you could get the OMGraphics to rendering into an
image used as texture for a 3d object, but you'd have to change the
architecture of the application to work that way.



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Received on Fri May 26 2006 - 11:08:44 EDT

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