Es una pequeña lista para la descarga de Orthofotos algunos son servidores gratuitos y otros con previo pago, pero es un buen punto de partida para descargar fotografías georefenciandas de algunas partes del mundo.
lista no es completa, pero su un buen punto de partida!
http://gisdata.usgs.net/
http://www.faygis.org/datasearch.cfm
http://www.cast.uark.edu/cast/geostor/raw_DOQ/index.html
http://sal.uamont.edu/pages/nsdd/Arkansas_State.htm
ftp://ccwgov.co.calaveras.ca.us/GIS/Raster_Data/Aerial_Photos/2002_2ft_Color_DOI/
ftp://ftp.ci.corvallis.or.us/pw/gis/orthophotos/
http://casil.ucdavis.edu/casil/kerncog.org/
http://www.faygis.org/datasearch.cfm
http://www.cast.uark.edu/cast/geostor/raw_DOQ/index.html
ftp://ccwgov.co.calaveras.ca.us/GIS/Raster_Data/Aerial_Photos/2002_2ft_Color_DOI/
ftp://ftp.ci.corvallis.or.us/pw/gis/orthophotos/
http://casil.ucdavis.edu/casil/usgs.gov/ http://www.landwateruse.water.ca.gov/basicdata/landuse/digitalsurveys.cfm
http://www.fcgov.com/gis/downloadabledata.php
http://www.udel.edu/dgs/dgsdata/hundreds.html
http://magic.lib.uconn.edu/cgibin/MAGIC_DBsearch2.plGeography=37811&Loc=0001
http://data.labins.org/2003/MappingData/DOQQ/doqq.cfm
ftp://gisftp.hicentral.com/AirPhotoImages/
http://casil.ucdavis.edu/casil/usgs.gov/
http://www.landwateruse.water.ca.gov/basicdata/landuse/digitalsurveys.cfm
http://www.udel.edu/dgs/dgsdata/hundreds.html
http://magic.lib.uconn.edu/cgibin/MAGIC_DBsearch2.plGeography=37811&Loc=0001
ftp://gisftp.hicentral.com/AirPhotoImages/
http://inside.uidaho.edu/
ftp://itoc.in-span.net/
http://cairo.gis.iastate.edu/map.html
http://inside.uidaho.edu/
ftp://itoc.in-span.net/
http://cairo.gis.iastate.edu/map.html
http://gisdasc.kgs.ku.edu/kgcc/
http://gisdasc.kgs.ku.edu/kgcc/
http://musashi.ogis.state.me.us/catalog/catalog.aspstate=2&extent=24k
http://www.mass.gov/mgis/laylist.htm
http://maps.dnr.state.mn.us/deli/data_search.html
http://www.lmic.state.mn.us/chouse/airphoto_usda.html
http://www.maris.state.ms.us/HTM/DataWarehouse/NAIP.htm
http://msdisweb.missouri.edu/data/naip/
http://gis.sedgwick.gov/view/
http://musashi.ogis.state.me.us/catalog/catalog.aspstate=2&extent=24k
http://www.mass.gov/mgis/laylist.htm
http://maps.dnr.state.mn.us/deli/data_search.html
http://www.lmic.state.mn.us/chouse/airphoto_usda.html
http://msdisweb.missouri.edu/data/naip/
http://nris.state.mt.us/nsdi/orthophotos/
ftp://www.co.missoula.mt.us/Surveyor/Horizx/MR_SID/
http://www.dnr.state.ne.us/databank/fsa03.html
http://www.dnr.state.ne.us/databank/lanc_doqq.html
http://njgin.nj.gov/OIT_IW/index.jsp
ftp://ims.bernco.gov/data
http://rgis.unm.edu/loader_div.cfmtheme=Digital20Orthophotos
http://www.nysgis.state.ny.us/gisdata/
http://lnweb02.co.wake.nc.us/gis/gismaps.nsf
http://www.state.nd.us/gis/mapsdata/download/
http://www2.ocgi.okstate.edu/2003img1/
ftp://ftp.ci.corvallis.or.us/pw/gis/orthophotos/
http://nris.state.mt.us/nsdi/orthophotos/
ftp://www.co.missoula.mt.us/Surveyor/Horizx/MR_SID/
http://www.dnr.state.ne.us/databank/lanc_doqq.html
http://njgin.nj.gov/OIT_IW/index.jsp
ftp://ims.bernco.gov/data
http://rgis.unm.edu/loader_div.cfmtheme=Digital20Orthophotos
http://www.nysgis.state.ny.us/gisdata/
http://lnweb02.co.wake.nc.us/gis/gismaps.nsf
http://www.state.nd.us/gis/mapsdata/download/
http://www2.ocgi.okstate.edu/2003img1/
ftp://imagery.pasda.psu.edu/pamap/
http://www.edc.uri.edu/orthosf/orthos/2003usda/
http://www.pasda.psu.edu/documents/datalist.cgi/naip
http://www.edc.uri.edu/orthosf/orthos/2003usda/mrsid.html
http://www.sdgs.usd.edu/register/index.html
http://www.capco.state.tx.us/Information_Clearinghouse/Orthoimagery_main.asp
http://agrc.utah.gov/agrc_sgid/naip.html
ftp://imagery.pasda.psu.edu/pamap/
http://www.edc.uri.edu/orthosf/orthos/2003usda/
http://www.edc.uri.edu/orthosf/orthos/2003usda/mrsid.html
http://www.capco.state.tx.us/Information_Clearinghouse/Orthoimagery_main.asp
http://agrc.utah.gov/agrc_sgid/naip.html
http://gis.vcu.edu/datausda.html
ftp://ftp.spokanemaps.com/
http://wvgis.wvu.edu/data/dataset.phpaction=search&ID=254#Download
http://edc.usgs.gov/
ftp://ftp.spokanemaps.com/
http://edc.usgs.gov/
http://nationalmap.usgs.gov/
http://www.usgs.gov/
http://terraserver-usa.com/