-------- Original Message --------
Subject:        RE: Free, open source map publishing tool - gdal2tiles
Date:   Mon, 19 Nov 2007 15:22:34 -0800
From:   Matt Fox <[log in to unmask]>
To:     'Maps, Air Photo & Geospatial Systems Forum' <[log in to unmask]>



Nicholas, I think all Andrew was trying to say is KML has its place and is
evolving more and more every year into a more sophisticated GIS tool.

Every data format has advantages/disadvantages.  KML's primary advantage is
making data available over the internet to a large non-technical audience
(such as library patrons).  5-10 years ago almost all GIS data required the
user to spend $1,000's on a complex GIS package.  KML opens all of that data
up to anyone with a web browser and/or viewer such as Google Earth.

No one is saying KML should replace SHP, GeoTIFF, JPG/JGW, etc. format for
archival or more complex GIS purposes.  But there is a reason most/all of
the major GIS platforms now support KML at some level.

Also, there are very few data formats that have the projection and position
information invisibly embedded in the file itself.  SHP files don't even do
that.

Matt Fox






> On Tue, 6 Nov 2007 12:30:18 -0600, Maps-L <[log in to unmask]> wrote:
>
>>>
>>> KML is quickly becoming a primary standard for distribution of
>>> geographic
>>> content on the internet.
>>
>> May be for mashers. But hardly any professional in the GI and remote
>> sensing industry uses KML for this purpose. It is simply not suitable,
>> it
>> has no data attribute or metadata carrying capabiities.
>
> This is incorrect. KML does in fact provide mechanisms for carrying
> additional data attributes, and is adding support for metadata.
>
> http://code.google.com/apis/kml/documentation/extendeddata.html

Oh pleeeze! This is a very low-level stuff. You are surely not seriously
suggesting using KML as a substitute for shape files, netCDF or DBMS
formats to distribute geoigraphic information. It is so inefficient and
unwieldy.





>
>>
>> Google has even submitted KML to the Open
>>> Geospatial Consortium.  Google Earth is simply a KML viewer and is
>>> certainly
>>> not the only program capable of displaying KML files.  NASA's World
>>> Wind
>>> (public domain) is just one example of another program that can view
>>> KML
>>> (although limited right now).  Even Microsoft Virtual Earth is starting
>>> to
>>> add KML viewing to its list of features.  In the next few years, we
>>> will
>>> see
>>> many other 3rd party applications (web browser plugins, etc.) that can
>>> view
>>> KML.  Also, don't forget that Google generates advertising revenue
>>> simply by
>>> listing a link to a website in its database.
>>
>> Exactly. Google Earth is gee-whiz but otherwise rather limited piece of
>> technology that is a means to attract people to a place where Google
>> displays advertising. Google Earth is a like a museum (perhaps art
>> gallery
>> is a better anology) where you can go and look, but you cannot do much
>> more than look. The general public like it for this reason, but for most
>> in the GI industry this is not what is wanted. They want to be able to
>> query, manipulate, take out of context, and combine with other
>> information, the information displayed on GE.
>
> This is true of GoogleEarth which is primarily a viewer, and lightweight
> content creation tools. But more tools are adding support for creating
> and
> manipulating KML. And part of the OGC effort of standardization is adding
> KML output to WMS. Other sites, like my own Mapufacture, also are
> building a
> large, open database of data sources and simple querying capabilities.
> GeoServer, and I believe ArcIMS 9.3, are two other widely used pieces of
> software adding KML support.

Manifold System 8.x can too, but that does not make KML a suitable format
for distributing geographic information types other than for those who
want to build mash-ups with GE or similar.

Read:

http://www.manifold.net/doc/export_drawing_kml_kmz.htm

You will note that KML only supports geopositioning wrt latitude-longitude
using WGS84.


>>> Another advantage of KML is that data created and hosted by many
>>> different
>>> institutions can all be integrated together seemlessly.  Try doing that
>>> with
>>> all the proprietary web-browser plugins that most map libraries are now
>>> using.
>>
>> Map libraries should be providing their scanned maps in standard image
>> file formats.
>
> And using KML as a mechanism for syndicating the location (geographic and
> URLs) is simple to do and effective.

No what it is, is unecessary. The location information should be invisibly
embedded in the data files.

----------------------------------------------------------------------
Nicholas J. Verge BSc. FGS
Henley-on-Thames, Oxfordshire, UK