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samrae

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About samrae

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  1. Hi, thanks for the responses: @yousef2233: Thank you, for your suggestion but unfortunately at this time I dont have time to apply more methodological analysis. At this stage I would like to try to understand and explain the relationship of species richness - NDVI correlation (if it exists) at a conceptual level for my results. Or how what the NDVI values indicate about the different land cover classes? @3dbu: It was actually a very simple application using the NDVI function in ERDAS Imagine. There were actually some software problems with the band combinations, which the forum was really great about providing advice about (see http://www.gisarea.com/index.php?/topic/2577-ndvi-values-from-spot-imagery/) I should probably explain that this NDVI section fits as a small component to a larger thesis where I have looked at land cover change (hence the land cover classes above) and also indigenous knowledge in the area.
  2. Hi there I am working with an NDVI image and was hoping to correlate the NDVI values with plant species richness, as there have been a number of studies that have used NDVI to predict species richness. However, in the various habitats I get different values: Forest* - medium values Pine plantation - medium values Riverine - high values Tea plantation - highest values *The forest areas are of old growth forest which should have the highest levels of biodiversity. But instead the riverine areas (and tea plantation) has higher values. I assume this is as NDVI is more closely correlated to new, live vegetaion (which emits more chorophyll). I was just wondering if I there would be any correlation to the species richness in this case then? And if there are other aspects, or insights that I may be missing... Thanks in advance!
  3. Hi, thanks for the comments. Yeah, it was 2.5m panchromatic wand 10m multispectral, so perhaps causing those artifact pixels.I also contacted the data provider and the images arent orthorectified, so rectification could be the other issue. Thanks.
  4. This topic is just out of interest, but something strange happened when I tried to pansharpen (resolution merge) with ERDAS IMAGINE. The SPOT 5 panchromatic and multispectral bands seemed to be slightly out of alignment, and result was a blurry output! I suspect its a data supplier issue. It also happened to someone in our department working in a different area, same data supplier and same software. I havent experimented with any other software yet. Thankfully, the pansharpened image isnt crucial for my workflow, but as its happened at least twice, I was wondering if anyone else encountered this?
  5. @nomlas and @rahmansunbeam - thank you, you were right! The bands were 3214. I've changed it to 1234 - the NDVI output looks much better now, and the water values are low as they should be!
  6. Hi, I've used 2011 SPOT-5 data to create an NDVI using ERDAS IMAGINE (the NDVI function available on the Raster toolbar). Ive got the output but am slightly concerned with the values. Its a rural area that consists of pine plantation(stretching from the south-west) , tea plantation (south-east corner) and natural forest (amongst plantation), but the highest NDVI value is 0.206. The forest, pine plantation and water seem to read this value or lower (to 0.128). 1. Is water meant to measure similar values to trees? 2. Is it not possible to see the difference between pine plantation and forest? Looking at the NIR composite the two classes seem more distinguishable 3. Are my values strange? Am I missing any vital pre-processing steps? Thanks Sam p.s. I was going to upload an image but dont have a place to upload it to.
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