This helped immensely for my own little vegetation analyses, thank you so much!

Thank you so much! I learned a lot and it is very easy to follow!

Thank you so much for the video! it was very useful and easy to understand, it helped me a lot!

thanks a lot , very useful and clear

Dear Dr. Hans van der Kwast. Thank you so much for such a wonderful video. I was comparing Landsat 9 (OLI) and Sentinel 2 (Level 2A) BOA images. I used different vegetation indices including NDVI and MNDWI. However, the BOA (L2A) NDVI looks weird. Do you recommend using Level 1C or L2A for vegetation indices? Thanks

Very good video

A lot thanks, Regards for you Sir

Thank u.

Thanks! Excellent video. One Q: Should we first calibrate the L1 image to surface reflectance?

@HansvanderKwast

3 жыл бұрын

Good question. Because NDVI is a ratio it's not needed. Only more sophisticated atmospheric corrections will have impact on the result.

thank you so much for the video. Do you know how to combine sentinel 2 images with black parts in the same raster??

@HansvanderKwast

2 жыл бұрын

Best to check the tutorials on the Semi-Automatic Classification Plugin. For example this one: fromgistors.blogspot.com/2018/04/cloud-masking-image-mosaic-and-land-change.html

There isnt a Sentinel option anymore, any idea why?

Thank you very much for this tutorial. One question: how can we calculate annual NDVI or monthly NDVI?

@HansvanderKwast

3 жыл бұрын

This video by my colleague explains how to do that with r.series: kzread.info/dash/bejne/f52iw9ulh7DHY7Q.html

Hi Hans. Thanks for that video. How can I extract a % per band?? I need to clasify a percentage per band to monitor a crop over time?

@HansvanderKwast

2 жыл бұрын

Not sure what you mean with % per band. NDVI is a single band raster. You can study changes over time by calculating NDVI for images of different dates. If you reclassify the values in the same way, you can calculate % change for each class. Not sure if you want that.

@josegarcia525

2 жыл бұрын

@@HansvanderKwast Yes I want to select a field and break down the NDVI values per pixel into perhaps 5-10 categories. Using this data I should be able to track the progress of the crop? I'm a real beginner to all this. I've just watched your percentage of land use video and I think this is the direction but in a smaller scale.

Thank you for the highly helpful video! I want to do the same procedure but with data for the country of germany. I can't find a fitting dataset on earthexplorer and the website won't let me upload the shapefile of germany since the polygone has more than 30 lines. Do you know where I can get the data? Again thank you for your help!

@HansvanderKwast

2 жыл бұрын

You just need a rectangle around your study area. You can create one in QGIS. Or you use the map in Earth Explorer instead of a file.

@nailujretuas2093

2 жыл бұрын

@@HansvanderKwast I tried using the map and drew a large rectangle around germany but earthexplorer gave me nearly 88.000 results with small areas that lie within my rectangle and not a dataset that most precisely resembles my rectangle.

@HansvanderKwast

2 жыл бұрын

If you want the whole of Germany with Sentinel you need to use Google Earth Engine. Otherwise go for coarser images, like MODIS. The problem is not the data, but what you want to achieve and then what to use for that.

How to classify and put the scale range for mangrove vegetation

Hi, thanks for your great video. When I did the raster calculation for NDVI it did not work. Appeared to calculate but did not show a layer. I checked correct projection and correct expression. Any ideas where I have gone wrong. Thanks

@HansvanderKwast

Жыл бұрын

If it calculated, you might find the file on your disk.

Can determine the area by color in hectares?

Hi thanks for the video. I just tried uploading a watershed KML file and I got an error telling me that the file is greater than 500 points. Is there a workaround to this limitation? thx

@HansvanderKwast

6 ай бұрын

For downloading the satellite image product from Earth Explorer, you only need a simple bounding box polygon. Earth Explorer will not clip the image for you, it will search for tiles that match with the extent of your KML. So you can just upload a simple bounding box in KML or shapefile format or zoom in to your area of interest and use that extent on the web page.

Do we not need to apply corrections?

@HansvanderKwast

2 жыл бұрын

It depends. If atmospheric conditions are homogeneous you don't need to apply atmospheric correction or convert to surface reflectance. That is because the index takes the ratio of bands.

the link is not working