RE: [OpenMap Users] VPFLayer problems with DNC (DNC17)

Hi Don, nice to hear from you.

As far as actually producing map graphics, the VPFLayer behaves perfectly: zooming, panning, redrawing, et al., all perform normally.

It is the information that is actually extracted from the DNC that seems erroneous. I've attached two cropped screenshots. The file "vpfview.gif" is taken from NIMA's VPFView program, and shows the hydrography area in light blue, and the hydrography lines in darker blue. The file "openmap.gif" is taken from my application using OpenMap, although I've taken out all of my extraneous layers so that all that can be seen is the DNC hydrography area in black, and the hyrdrography lines in gray. These shots are both taken of the area south and east of Long Island. You'll notice that VPFView outlines Long Island, and the islands of Martha's Vineyard and Nantucket. The shot from OpenMap doesn't show much of Long Island, and definitely draws water areas over where Martha's Vineyard and Nantucket should be. Also, there is a huge swath of area where no data is drawn. It follows the contours of the hydrography lines in some areas, and follows lines of latitude and longitude in others. Perhaps this
suggests that certain specific times contain malformed VPF data that VPFView is tweaked to handle, whereas OpenMap is not? I did download a newer version of DNC17 (specifically, the gen17a library) and that did not help. I can probably hunt around for a public link to this data if it might help.

Thanks,
-Tim Nolan

-----Original Message-----
From: Don Dietrick [mailto:dietrick@bbn.com]
Sent: Friday, October 10, 2003 4:07 PM
To: Nolan Timothy P Jr NPRI
Cc: 'openmap-users@bbn.com'
Subject: Re: [OpenMap Users] VPFLayer problems with DNC (DNC17)

Hi Tim,

On Friday, October 10, 2003, at 03:58 PM, Nolan Timothy P Jr NPRI
wrote:

> Hello,
>  
> I am using OpenMap to view NIMA's Digital Nautical Chart (DNC),
> specifically DNC 17 (covering most of the eastern US seaboard).
> I am adding VPFLayers programmatically to my LayerHandler, and all the
> Harbor and Approach libraries display correctly.
> However, I would like to use data from the Coastal and General
> libraries, but their coverages are drawn improperly.
> Specifically, south and east of Long Island, hydrography area data is
> drawn where it does not exist, and not drawn where it does.
> Interestingly, the data areas are bordered by hydrography lines, so
> perhaps this has something to do with the problem.

So besides being drawn in the wrong place, does it react property to
projection changes, moving with the map and displaying consistently?
How do you know they are in the wrong place (what data are you
comparing the location to)?

We don't have much DNC data, so it's hard to get a bead on what is
happening. Got a screenshot?

- Don

>  
> This problem affects both the current release version (4.5.4) and the
> October 4th snapshot of the 4.6 beta.
>  
> Any information would be greatly appreciated.
>  
> Thank you very much,
> -Tim Nolan
>  
>  
>  
>  
> ____________________________________________
> Timothy P. Nolan
>  
> Naval Undersea Warfare Center
> Code 2233
> 1176 Howell St.
> Newport, RI 02840
>  
> (401) 832-5284
> nolant@npt.nuwc.navy.mil
>  
>

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

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