Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!sdd.hp.com!ucsd!pacbell.com!att!cbnews!cbnews!military From: IO00672%MAINE.BITNET@VM1.gatech.edu (Sloth) Newsgroups: sci.military Subject: Re: Tomahawks Message-ID: <1991Jan24.033445.19610@cbnews.att.com> Date: 24 Jan 91 03:34:45 GMT References: <1991Jan18.005043.9622@cbnews.att.com> Sender: military@cbnews.att.com (William B. Thacker) Organization: University of Maine System Lines: 32 Approved: military@att.att.com From: Sloth Jon C. R. Bennett writes: >It is quite possible to build a 3D map from 2D data, the opening credits >to CNN's "Technology Today" which is view flying over a 3D terain (San >Fransico Bay) was created from 2D Landsat data by having a computer >compare the shadows cast by the sun at different times of the day. It is >also possible to get 3D data directly using radar equiped satalites, which >are reported to have very good resolution (measured in feet or less). The Landsat satellites run in a sun-synchronous orbit. That is, the orbital plane is such that it precesses across the Earth at the same rate as the Earth's rotation. Thus, no matter where the images are taken, they all are taken at the same local time (nominally 9.30a) and have the same "sun angle." This is necessary so that different images of the same area are consistant in their lighting. Otherwise, change detection (comparison of an area over time) would be very difficult if not impossible. I'd suspect that if CNN's graphics used Landsat imagery, it would have been created by integrating a Landsat image with a digital elevation model of the same area. ]:-)> ---> Malcolm Fuller Email: IO00672@MAINE.MAINE.EDU Surveying Engineering Department MALCOLMF@MECAN1.BITNET University of Maine Malo Periculosam Libertatem Quam Quietam Servitutem