The Daily ACK‘s Alasdair Allan has a great find on arXiv.org, the online repository for physics papers:

Sky in Google Earth: The Next Frontier in Astronomical Data Discovery and Visualization

It’s by the people who built the Sky functionality in Google Earth, and the whole thing is a worthy read. Some of the highlights that caught my eye:

The underlying imagery used in Sky resides in a lat/long projection (Snyder 1926). This results in substantial distortion at the poles even when re-projecting onto the sphere. Thus, for regions within five degrees of the pole we replace the original images with a lower resolution view of the sky derived from the Tycho II catalog (Høg et al. 2000). […]

The underlying projection and registration of images in Sky is based on the technology used in Google Earth. This provides a mature visualization platform on which to develop Sky, a very large user base, a simple but extensible interface and a well-defined and on-going support and development mechanism. It does, however, lead to a small number of trade-offs — related to the way geospatial data is served — that were made in the course of adapting the system to serve astronomical data. […]

As with Google Earth, the basemap is not static and we anticipate continued improvements as we refine our treatment of the current imagery and new large-scale datasets become available. […]

It is worth noting that planets’ and the Moon’s icons are not scaled according to their actual appearance on the sky so that they can be more easily distinguished from the background stars. […]

(If that was the reasoning behind not showing real-size icons then I think this was a mistake. In the Google Earth environment, you can always zoom in more to see detail if you wish. More likely, the limitations on controlling the size of an icon via KML as rendered by Google Earth is to blame. Another problem that will need to be solved: Which planetary icon comes before which, and when? Layers in Google Sky behave like Ptolemaic spheres inside spheres, but planetary orbits do not. Sometimes Venus occults Mercury, sometimes Mercury occults Venus…)

The KML tag name GroundOverlay is inherited from Earth, but these are simply images projected against the basemap in Sky. […]

(Pace Vint Cerf:-)

As mentioned previously, since Sky shares a rendering engine with Earth, the geometry of the sky is, in fact, a slightly oblate spheroid (technically, the WGS84 projection). The GIS community has developed a number of tools for handling re-projections of images using this geometry, most notably the Geospatial Data Abstraction Library (GDAL). This software can warp images from one projection (including a tangent plane) to another and encodes the geometric information necessary for registering the image on the sphere in either an image header (analogous to a FITS header) or an associated “world file”, depending on the image format. While users may want to become more familiar with the GDAL software themselves, we provide a simple, open source tool wcs2kml which will read in an image in a variety of formats and WCS information from a FITS header and generate a properly warped image and overlay KML for you. This tool is available in both Python and C++ versions.

[What! The sky is not a perfect spere? :-)]

Every day at 9am and 1pm, a small group of people who wait in line get to pay 100 Egyptian pounds ($18) to climb into the Great Pyramid of Khufu and all the way up to the burial chamber. Cameras are confiscated at the entrance, because otherwise who will buy the postcards? Luckily my Nokia N95 was let through as it was deemed just a phone.

Standing in the middle of the most impressive architectural feat ever (in my opinion) is a humbling moment. It’s very warm in there, and there is a very deep and pervasive rumble, which we eventually sourced to the ancient ventilation shafts, through which the air was rushing. I took out my camera phone — not surprisingly, there is no reception inside a 7 million tonne stone monument.

A visiting friend happened to be walking up the steps of the Great Gallery so I took a picture. Where exactly were we? ATF’s accurate 3D model of the pyramid provides the best possible contextual information, and since you can now accurately position photos on Google Earth, why not combine the two?

Download ATF’s model of the Great Pyramid, then download this photo, added using version 4.2’s <PhotoOverlay> tag, to see where inside the pyramid it was taken.

A disadvantage of living in Cairo is that The Economist doesn’t arrive at newsstands until Monday, Sunday if you’re lucky. Fortunately Tech Consumer points the way to the online edition of this week’s Economist Tech Quarterly insert, whose leader article is one of the best overviews I’ve read of the geoweb, neogeography, virtual globes, mashups, and the security and privacy implications. There’s references to Snow Crash and copious quotes from interviews with Google Earth’s Michael Jones and John Hanke and Microsoft Virtual Earth’s Vincent Tao: The world on your desktop. It is free to read without a subscription (at least for me, at the moment).

That this article should appear just now and so prominently in a newspaper with a large readership in the business world is a bit uncanny, given this week’s revelation that Google Earth Free has become a legitimate tool for use at work. All those CEOs calling their CTOs asking why they don’t have Google Earth installed on their corporate laptop can now be told there is no legal reason why not:-)

While there’s not much news in the article for those who have been reading the geoblogs closely these past few years, for everyone else this is a lucid and penetrating introduction to the geoweb. If your mother has been wondering what precisely this geoweb is and has been complaining how she doesn’t understand any of it, send her the link to this article. I have:-)

Frank Taylor brings news of the newly updated release notes for Google Earth version 4.2 and rightly homes in on a major change: Updated terms of service for Google Earth Free and Plus.

In brief: You can now use it at work for “internal use”.

The most important bit of the new license now reads like this:

1. USE OF SOFTWARE; RESTRICTIONS

Use of Software. For an individual end user, the Software is made available to and may be used by you only for your personal, non-commercial use according to these Terms of Service and the Software documentation. For a business entity user, the Software may be used by you and your employees for internal use according to these Terms of Service and the Software documentation (individual end users and business end users are collectively referred to as “You” herein).

Restrictions. You agree not to use the Software in connection with or in conjunction with a system in a vehicle that offers real-time route guidance or turn-by-turn maneuvers. You agree not to use the Software for any bulk printing or downloading of imagery, data or other content.

Whereas previously we had this, in version 4.1:

1. USE OF SOFTWARE The Software is made available to you for your personal, non-commercial use only. You may not use the Software or the geographical information made available for display using the Software, or any prints or screen outputs generated with the Software in any commercial or business environment or for any commercial or business purposes for yourself or any third parties. You may not use the Google Software in any manner that could damage, disable, overburden, or impair Google’s services (e.g., you may not use the Google Software in an automated manner), nor may you use Software in any manner that could interfere with any other party’s use and enjoyment of Google’s services.

(My italics) A “Find Differences” in BBEdit finds very few further differences between the two texts. Lawyers wanting to peruse both texts can use this link to the license from version 4.1. One minor change in version 4.2 is a link to a standardized Google policy on privacy (instead of spelling it out in the text). Google’s data licensors are also referenced together with Google when posting disclaimers, and this paragraph is new:

3. PROPRIETARY RIGHTS

a. Google. […]

b. Third Parties. Data for map content in the Software is provided under license from Google’s licensors, including by Tele Atlas North America, Inc. (“TANA”) (the “TANA Data”), and is subject to intellectual property rights owned by or licensed by TANA and such other licensors. You agree that you will not engage in, and may be held liable for any unauthorized copying or disclosure of this material. By using the Software, you agree to make TANA a third party beneficiary of this agreement. Your use of TANA Data is subject to additional restrictions located in the following Legal Notices page: http://www.google.com/intl/en_us/help/legalnotices_maps.html.

So what does “internal use” mean for a business user? I am not a lawyer, but my understanding is that Google Earth Free finally becomes a proper universal browser of georeferenced data. You no longer need Pro to do geoweb surfing at work, or to search and view KML files, even for doing business-related research or intelligence gathering, much as you would use an ordinary web browser to gather information from the ordinary web. Nevertheless, I suspect this new license does preclude businesses from using the Free application to produce commercial geospatial products. That would result in an “external” application of Google Earth. But, again, IANAL. Google Earth’s “Software documentation” is given as a source for further explication, but the online legal FAQs are currently still the old ones.

Also of interest is the restriction that prevents third parties from offering a sat-nav solution for cars that involves running Google Earth, much like the setup demoed by Volkswagen 18 months ago.

(Note: I’m still working setting up a reliable internet connection (again) in a very hot Cairo, so pardon the flagging blogging around here for another week.)

Looking for a neogeo job?

• Google is looking for a Google Earth outreach KML evangelist, over on NeoGeo Jobs.
• The UNDP is looking for a KML-savvy web content manager for full-time home-based work for six months. it looks like the Millennium Development Goals are going to get their own outreach website — The MDG Monitor, “which will be launched in September as a partnership with Google” — and they’re looking for someone to manage it.

Summer is ending in Sweden; after a final brief jaunt to the Stockholm Archipelago this weekend, I’m heading back to Cairo. In the meantime, Google Earth news hasn’t stood still:

• Flight Sim: Marco Galotta discovers a fully-fledged flight simulator hidden inside Google Earth! Ctrl+Alt+A gets you there in Windows, Command+Option+A on a Mac. There’s an official page listing flight simulator keyboard shortcuts on earth.google.com.
• Google Earth User Guide: The Google Earth user guide has been updated to reflect the changes in version 4.2 beta, including system requirements.
• Pattern recognition: An intriguing thread wherein DigitalGlobe is looking to have its imagery be made more accessible by experimenting with the Numenta Platform for Intelligent Computing (NuPIC) and its hierarchical temporal memory system (HTM), which aids with pattern recognition.
• Send to car: While Google Lat Long Blog announces that Google Maps’ “Send to Car” feature for directions will soon be available to all European BMW Assist customers, a press release by Mercedes announces that US customers will soon be able to start using the same feature, and additionally also send directions from Yahoo Maps. And Digital Urban looks at 3D sat nav for cities, to be rolled out by Tele Atlas in the coming months.
• FlashEarth popup: Over on the nearby.org.uk blog, Barry Hunter hacked together a network link that shows the view from the FlashEarth mapping application inside a popup in Google Earth (for PC only). He then goes and tweaks it, producing this final version.
• More video: Other content taking advantage of KML 2.2: Digital Urban flags the Virtual Tourism Blog‘s KML layer of georeferenced videos

Alasdair Allan’s latest post on The Daily Ack on making Google Sky interoperable with the Plastic communications protocol for virtual observatories is worth a long expository article all to itself. Considering my time constraints right here and now, it will have to do with a short hearty recommendation all to itself. It’s a must-read.