I'm using ENVI 5.3 to do the processing, but if you know how to do this from any open source GIS software it's also valid :-).
I read an article that mixes both Modis MOD15A2 (LAI product) with Landsat 7 (ETM+) or Landsat 5 (TM) [Gao, F et al., 2012 ], but it is not what I'm looking for. I just want to use L8 images. If you know any way to do this or know any articles that could be usefull for this I'd be really grateful if you could share it.
The truth is that I'm trying to find an "easier way" to retrieve LAI in comparison to the mix of Landsat with MOD15A2, this is due to the fact that I really need to do a lot more things besides from retrieving LAI for my thesis. So any "easier" way would be much appreciated. Thanks in advance.
Hi Jorge,
LAI is not directly measured by remote sensing sensors but a property of the vegetation (m2 leaf area / m2 ground area) often estimated in the field. Optical remote sensing sensors measure spectral reflectance from for example the vegetation canopy which is found to be strongly correlated to the LAI of that particular vegetation. Therefore, Gao et al. (2013) use some kind of regression model to relate field estimated LAI to the spectral reflectance derived from remote sensing products. This model can be used to predict LAI in places where LAI was not originally measured in the field but remote sensing data is available. So, without field estimated LAI you cannot derive LAI from Landsat 8 images unless you find someone who already developed a model for this and you can use that model.
Hope it helps.
Cheers,
Thomas
Thank you Thomas,
I'll definitely take a look at that article. And as you were saying, I'll retrieve LAI from field work, but I'm trying to find some physical-based model or regression model that have had good results from using only Landsat 8 images.
Thanks again!
Jorge.
Hi Jorge,
I did not know you measured LAI in the field, that's great! I couldn't find any papers that use LS 8 data for estimating LAI however, the "sensitivity to vegetation" of LS7 and LS8 is quite similar from my experience. Because the relationship between spectral reflectance and LAI is different in different environments I think it would be best to develop your own regression model and look how wel it predicts LAI. Maybe a simple regression of LAI against NDVI or EVI? Good luck!
Cheers,
Thomas
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