Hola Adrian. EL Instituto Geográfico Militar tiene un archivo fotográfico de vuelos aerofotogramétricos de todo Chile, entre las cuales hay varios vuelos del norte del país. Yo usé algunas fotos tomadas entre 1954 y 1956 para un artículo ( https://www.nakala.fr/nakala/data/11280/435bd828). Hay dos de los vuelos que son los mejores, ambos mediados por la Fuerza Aérea de Estados Unidos, los llamados Trimetrogon (1944-1945) y los Hycon (1954-1956). Se pueden comprar las fotos en distintos formatos. Creo que incluso hay un catálogo en línea.

Saludos

Gracias Benjamin, estaba al tanto de la disponibilidad de las imagenes del IGM (pero esta bueno saber los aspectos tecnicos), al igual que las del Archivo Bello de la UChile. Sin embargo, estaba buscando alternativas de acceso libre. Tambien estan disponibles las imagenes satelitales CORONA, pero al igual que las del IGM tienen algun costo asociado por imagen.

Hello Adrian, I can see that you mention the "use of freely available satellite imagery to detect archaeological sites". Does this mean that you need only aerial photographs? Or high-resolution satellite data (such as Landsat (30 m resolution), or Sentinel 2 or 1 (20 m resolution and 10 m for PAN band) can do the job? If yes, then the normal satellite data repository such as those of NASA (i.e. USGS Earth explorer, Glovis, etc.) or ESA (ESA Earth Online, Copernicus, etc.) can be very useful. Another final option would be to create you very high-resolution aerial photographs using google earth and tools such as SAS Planet, etc. But the last option would take you ages if your study area is very big (i.e. national level).

Hi Maurice, and thanks for answering my question. Sorry, my initial question was not clear enough as I did not want to overextend the explanation of what I am doing for my thesis. Nevertheless, yes, I am now in the stage where could be interesting to explore aerial photographs for assessing the destruction of archaeological sites, and at the same time to be able to look at areas nowadays highly disturbed by industrial development.

About your recommendation of looking at Landsat, Sentinel, and also browsing information available in the different portals of NASA and ESA, indeed I agree with you that is the way to go. I actually did that already to evaluate what was the quality of this imagery in my area of interest. In the end, I opted for using Google Earth and Bing Maps as at the moment of the survey (2018) were the best available.

Hi Adrian, I am so happy to hear that you are progressing well, and that you could meet your research requirements. True, recently there have been great evolutions in the area of remote sensing and related applications, and I am sure that more better products will be very helpful as well. More options such as images fusion (for images with some differences) or spectral unmixing techniques can also handy if considered, but of course, this will depend on the research scope since some of these may become like new research project by themselves. Kindly share with us some of the publications once they are available, your research sounds so interesting and I would be grateful to hear about the progress, results, etc.

Hi Adrian,

Maybe interesting sources of High Res imagery are:

https://www.zoom.earth

and

Google Earth

Zoom Earth gives near real-time High Res imagery for Northern Chile from 1999 till now. That's a 21 years time-lapse. Maybe that's enough for your multi-temporal study. You can apply different techniques to find urban land-use changes for Northern Chile.

You can use Google Earth to find the exact geolocations of places which show strong land-use changes at street level.

Success,

Frank

Maurice Mugabowindekwe thanks very much for your kind words. I was not aware of the images fusion nor the spectral unmixing techniques, it sounds really interesting. I may ask you later more about that if you don't mind as I am thinking once the PhD comes to an end to experiment with the application of different remote sensing techniques on this same area in Chile.

Once I have publications of my project will upload them onto RG.

All the best!

Adrian

Hi Frank Veroustraete ,

I did not know about the zoom.earth webpage, it looks impressive. Thank you for the recommendation. Indeed, the method you propose to follow is the one to do.

All the best,

Adrian