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closeWhat about the date range of GSV photo
Posted by RasEB on 13 Oct 2013 at 10:51 GMT
Seasonality is discussed but not the date (year) difference between the field data and the GSV data.
The field data was collected between 2007 and 2009 but we have no information about the date of the GSV data.
GSV has started on On July 2, 2008 [https://en.wikipedia.org/...] with few places ; Orléans was added on December 2, 2009 and more location in 2011. Could the differences between field data and GSV be just a distribution change between the field data and the shooting date of GSV ?
Can we get the date of shooting (via the API ?) ?
You discuss the importance of GSV in the future to assess environmental change, but the problem of this database is that it is not free ; we have no way to be sure of the persistance of the data which can be shut down by Google whenever it wants or change the conditions of use. It calls for a public database...
Interesting paper though. Thanks
RE: What about the date range of GSV photo
jprossi replied to RasEB on 25 Oct 2013 at 16:44 GMT
Thank you very much for your comments.
We address 3 points below:
1) Could the differences between field data and GSV be just a distribution change between the field data and the shooting date of GSV ?
Most of the discrepancies between GSV and field data occur in the Beauce region i.e. our small sampling grid. In that place, Google pictures were taken in 2009 and 2010. We collected the field data before or during that period therefore this could not lead to false negatives – the main source of difference between GSV and field data. False positives may appear when pictures are taken after field observations in the case of a dynamic process such as a spatial expansion but in our study, we found no false positives. Therefore, we have the feeling that the differences between shooting and field observation dates are not a major concern in our study.
However, it is clearly an important source of possible mismatch between field and GSV data in other cases hence it deserves attention in future use of GSV. Note also that the dates that can be seen in the GSV screens are copyright dates with no absolute certitude that the pictures have been taken at that date. This point appeared recently during discussions following the publication of the paper.
2) Can we get the date of shooting (via the API ?) ?
We weren’t able to get this information from the API.
3) You discuss the importance of GSV in the future to assess environmental change, but the problem of this database is that it is not free ; we have no way to be sure of the persistance of the data which can be shut down by Google whenever it wants or change the conditions of use. It calls for a public database...
We agree with you at 100% A public database would also guarantee that the sampling protocol and all technical information are available plus a possible access to archives.
Again, thank you for your comments.
JR + JPR
RE: RE: What about the date range of GSV photo
RasEB replied to jprossi on 30 Nov 2013 at 16:15 GMT
Thank you for your answers.