[Xastir] US Topo GeoPDF?

[Fred Hillhouse]

Hi Lynn,

I found that right after I sent my email. I wanted to see how my other
software found the tile and fired up Wireshark.

It turns out, I have been tapping this lot (in your link) for some time and
converting them to PNGs.

Best regards,
Fred, N7FMH


-----Original Message-----
From: xastir-bounces at lists.xastir.org
[mailto:xastir-bounces at lists.xastir.org] On Behalf Of Lynn W. Deffenbaugh
(Mr)
Sent: Monday, March 19, 2012 14:00
To: Xastir - APRS client software discussion
Subject: Re: [Xastir] US Topo GeoPDF?

http://tinyurl.com/6nrnl2c - but beware that the *.PNG files are actually
JPEGs in PNG file names.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 3/19/2012 1:50 PM, Fred Hillhouse wrote:
>>> With the correct decoding, the SlippyTiles can be accessed from the
> National Map.
>
>> Are you suggesting adding National Map support to Xastir, similar to 
>> the
> online osm tiles feature? If we are lucky, maybe the tile specs are 
> the same! I don't think the USGS wants their tiles being used with 
> other services, but I haven't asked.
>
> You are not so lucky about the tile spec. From Wireshark, the request 
> looks like this:
> [truncated] GET
> /ArcGIS/rest/services/DRG/TNM_Digital_Raster_Graphics/MapServer/export
> ?dpi=9
> 6&format=png&bbox=-7871179.42469431%2C5320017.16864827%2C-7868733.4397
> 8918%2 
> C5317571.18374314&bboxSR=102113&imageSR=102113&size=1024%2C1024&f=imag
> e
>
> I looked briefly at how to specify the bounding box (bbox):
> http://help.arcgis.com/en/arcgisonline/content/index.html#//011q000000
> 020000
> 00
>
> I will have to play around now myself. It shouldn't be difficult to
master.
> Personally, I use 256x256 tiles and save them in the same way the OSM 
> tiles would be saved (Z/X/Y.png). I am using APRSIS32. For Xastir, if 
> a different map size is needed, then the bounding box could cover a 
> whole area. I actually tapped the USGS maps and generate tiles using 
> bounding boxes for use in APRSIS32. I like them better than the CycleMap
tiles from OSM.
>
> This is Slippy map:
> http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
>
> National Map was added to ExpertGPS/Win32 recently which I have been 
> using for 10+ years. It appears he watches the licensing closely. It 
> would be wise since his product is commercial.
>
> > From a license aspect, I have looked through the license and 
> > concluded that
> for my no-commercial use, I would be okay to download the map. I am 
> not a lawyer so my interpretation might be flawed.
>
>> Alternatively, you can get seamless USGS Topo tiles from an ESRI tile
> server. Looking at the license, I think it would be fully compatible 
> with Xastir as long as we don't exceed the transaction limit. The tile 
> format is Google/Bing--is this the same as OSM/Mapnik?
>
> Yes, Google and Bing and many others use this format. It appears to 
> have become the standard web display. Some servers do a "invert Y" and 
> the same basic format. I say same basic format because the X and Y may 
> be reversed in a web address or other little items are added, such as 
> x=## rather than just x. [For the curious: Inverted Y = (2^Z-1)-Y. I 
> found aeronautical/nautical charts that use this.]
>
> As an aside, I save all my tiles on the hard drive. My station is 
> mobile without an internet connection. For areas I play in, I have 
> gathered appropriate tiles. The obvious benefit is I always have a map.
>
>
> Best regards,
> Fred, N7FMH
>
>
>
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>

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