Satellite Imagery starting points

I often have requests from readers who need help locating starting points for data resources. Today one request needed to locate some satellite imagery providers. Indeed there are many of them, however, a few good starting points include:

TerraServer http://terraserver-usa.com/

NASA and NOAA have loads of imagery (see http://www.ghcc.msfc.nasa.gov/GOES/)

as does Digitalglobe.com and http://www.globexplorer.com/

Globexplorer - http://imageatlas.globexplorer.com/ImageAtlas/view.do

This is also a great resource - http://earthnow.usgs.gov/

See also http://www.geobserver.com/worldview_eng.php

and UNOSAT http://unosat.web.cern.ch/unosat/

We also have a decent directory of public and commercial resources at http://www.gisuser.com/content/category/10/168/41/

Satellite Imagery starting points

Convert from NAD27 to WGS84

This datum conversion is often a pain for people. The following are a couple of utilities that you might find useful:
You could try this routine at http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html

Or from the USDA - http://www.fs.fed.us/database/gps/datum/index.htm

See also coordtrans (with free trial) http://franson.com/coordtrans/

Convert from NAD27 to WGS84

Free US Township and Range Data download

A little know secret is that Free Township Range data for each State can be had via the delorme Xmap site. Simply jump to http://www.delorme.com/xmap/ and scroll down to the supplementary data section. NGS Benchmarks are also available for purchase for a very small fee.

The PLSS layer includes the following attributes for each section polygon:

• TWP – Township number
• TWP_DIR – Township direction, usually N (north) or S (south) of the survey baseline
• RNG – Range number
• RNG_DIR – Range direction, usually E (east) or W (west) of the principal meridian
• SEC – Section number

Free US Township and Range Data download