actually these satellites are not reliable to use as only way.
remote sensing has always error but you can do it with approximately good results. test it for an area with in-situ, study the errors, then use for other region.
We know ground measurements are important but we are trying to create information about the past and we do not have measurements for taht time over our region of interest.
Therefore, I am looking for possibilities without in-situ measurements.
Landsat is the best option if you want free previous images with low resolution. But for higher resolution you can go for SPOT images. Sentinel will provide you data from only 2015, not good for creating information about the past. You can generate model using present in-situ and satellite data, and then apply the model to get past information using either Landsat or SPOT.
Thanks for your answer. We already have plenty of different satellite images from SPOT, Sentinel and Landsat as I mentioned in my question. I am looking for deeper explanation of possible models to be used for LAI generation. I am not looking for regression based models relating satellite and in-situ data.
We are trying SNAP now, thanks to comments of Andreas. Any suggestions on some physical models and other approaches is appreciated.
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