Hi Kennedy,
There are some images that take longer to load, I'm not sure why - it
seems to be happening in the JAI code. I haven't really studied the
problem, I don't know if those images are compressed or have some kind
of colormodel representation that creates more work.
The GeoTIFF images generally have the location information embedded
inside the image. The .tfw world file might be an extra file for
image display programs that don't know how to read those tags, but
generally you can use any image format with a world file. For
OpenMap, if you specify an image that's not a GeoTIFF the code will
look for the world file. The extension of the world file depends on
the format extension of the image file name - for PNG it should
be .pgw, JPG should be .jgw, GIF should be .gfw. Basically, the first
and last letters of the extension and then a 'w'.
Hope this helps,
Don
On Jul 7, 2009, at 9:34 AM, Davidian wrote:
> Hello all.
> I'm hoping someone can help me with the problem I am having with
> displaying Geo-referenced imagery in OpenMap.
>
> Using tips that I've found on this forum, I've been able to
> successfully display GeoTIFF images in OpenMap, and that works fine.
> My problem is that the file sizes must be too large because OpenMap
> takes too long to load those images. For example, a 27MB GeoTIFF
> image takes about 20 seconds to load/display in OpenMap, which is
> way too long for the users to wait.
>
> My question is this: Does anyone have any tips or information that
> will help me do either (or both) of the following?:
>
> 1) Make "large-ish" GeoTIFF images load more quickly.
>
> 2) Load geo-referenced imagery from a different file format. The
> person who provides me with the imagery said that he could get the
> file sizes down if we could use GIF, PNG, or JPG file formats, but
> I'm not sure that those formats will work. The GeoTIFF file has a
> corresponding world file (.tfw) extension which specifies the
> location of the imagery. Is there such a thing for these other image
> formats?
>
>
> Thank you very much in advance for any help you can provide.
>
> -Kennedy
>
> View this message in context: Need help displaying geo-referenced
> imagery.
> Sent from the OpenMap mailing list archive at Nabble.com.
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Received on Tue Jul 07 2009 - 13:08:34 EDT