Hi Steve,
Looking at the image, I doubt that it was taken at the full resolution
of the data. I've seen that effect before, and it occurs when you are
zoomed out past the native scale of the image. There are a couple of
things you can do to test this out. First, you can run the RpfFrame
directly on some of the frame data. The path to the frame is the
argument to the class:
java -classpath <path to openmap.jar>
com.bbn.openmap.layer.rpf.RpfFrame <path to a frame file>
This will print out all of the attributes of the data and launch a
frame so you can look at it in its native scale.
Likewise, you can run the RpfTocHandler to look at the table of
contents file, and see what the data creator thought the scale of the
images should be. You would run that class as an application on the
top level RPF directory that contains the A.TOC file.
The effect is being caused by the scaling OpenMap is doing on the
tiles to make it fit the projection parameters. If the
MapRequestHandler was being given a request where the projection was
in the native scale of the charts, it would be clear of the effects.
The tiles are being scaled using a Bilinear algorithm, and that's
causing the problem.
I've made changes to the OMScalingRaster class that lets you set the
scaling transform type, so a nearest neighbor algorithm could be used
instead (although that has different problems, it gets a little blocky
at times). I've also updated the RpfLayer so it can set the scaling
transform type on the tiles. Those changes will be available in the
beta shortly. I could advise you on how to update your version of
OpenMap if you need me to.
Hope this helps,
- Don
On Thu, Feb 17, 2011 at 5:21 PM, Steve Tarter <steve.tarter_at_zedasoft.com> wrote:
> I have an application using OpenMap that serves up CADRG data rendered by
> com.bbn.openmap.layer.rpf.RpfLayer using
> com.bbn.openmap.image.MapRequestHandler. This has been in use for a number
> of years.
>
> We have a new customer that has brought a new set of CADRG files. The
> charts represented within this dataset include thin grid lines that fade in
> and out across the rendered image, even when the requested scale is the same
> as the map. Attached is an example of the rendered map. I have tried
> requesting JPG, PNG, and GIF formats without any noticeable difference. I
> have also tried turning on the doAntiAliasing flag in ImageServer with no
> effect.
>
> My customer has indicated that they use this same series of chart data with
> another application without displaying this artifact. Of course they are
> unable to share the application they are using, or show it to me.
>
> Is there another (free) viewer of CADRG files that I can point at this data
> to verify that the problem isn't with the source data?
>
> Is there a property I can adjust within OpenMap to increase the quality of
> the image?
>
> Thanks in advance for any help.
>
>
> Cheers!
>
> Steve Tarter
>
>
>
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Received on Thu Feb 17 2011 - 23:06:58 EST