Timeline for How to remove abnormalities from the Green vegetation fraction
Current License: CC BY-SA 3.0
14 events
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| Nov 5, 2014 at 16:37 | comment | added | Waseem Ali | @WhiteboxDev. With reference to your detailed answer, I have resolved little problem but still there is another problem to be resolved. I have calculated the ndvi values of 5 successive images detail detail on another post. I need your help to scale the palette. I don't understand how to fix the palette to see the relative change in successive imagery of green vegetation fraction. I have also attached the paper there to whom I am following. | |
| Oct 29, 2014 at 14:34 | comment | added | Waseem Ali | @WhiteboxDev. So how could i expect these ranges in my data set. Is there any clue to deal with such matter. | |
| Oct 29, 2014 at 12:46 | comment | added | WhiteboxDev | @WaseemAli Your raw range of values will always be different than theirs (without rescaling) because you're dealing with a different landscape. Even in the same landscape the NDVI will differ through time. I don't think that you should expect your range to be the same as theirs. | |
| Oct 29, 2014 at 12:40 | comment | added | Waseem Ali | @WhiteboxDev. please share any tutorial or book material to understand this. Did you read the research paper i have attached? Actually author have chosen the NDVI threshold to derive the GVF as mentioned in 2.3 section (min 0.05 and max 0.70) and this is problem how to chose that range for my study area. How these fractional values be presented onto the colour map as in Figure 4. Should I have to rescale these float values to integer values into 256 bit to represent the colour palette Or float values can also be displayed in arcGIS 10? I was actually confused to solve this matter. | |
| Oct 29, 2014 at 11:49 | comment | added | WhiteboxDev | @WaseemAli If you have a variable that ranges from Xmin to Xmax and and you want to rescale it to the range Ymin to Ymax then for any member of X calculate the output Y as Y = Ymin + (X - Xmin) / (Xmax - Xmin) * (Ymax - Ymin) This is the general formula for a linear rescaling. | |
| Oct 29, 2014 at 6:30 | comment | added | Waseem Ali | @WhiteboxDev. I realized after your detailed reply that i was using display min and max value used to scale the palette rather than the actual range of image data. I need a little more help to how should i scale them accordingly so that i could make the graph as Hu and Jia did in figure 4 to see the relative change of each successive images.paper. | |
| Oct 24, 2014 at 7:41 | comment | added | Waseem Ali | @WhiteboxDev. I have append some information in my another post, you can view it the data and my requirement there please.link | |
| Oct 23, 2014 at 14:38 | comment | added | Waseem Ali | @WhiteboxDev, May be I was unable to explain of my question, I have derived NDVI map of same area of years 1992, 1998, 2002, 2010 but the ranges of every years representing 0-0.33, 0-0.45, 0-0.33, 0-.32, 0-0.30 respectively are different, how can I make them normalize into the same range so that I could see the difference of each successive images. | |
| Oct 22, 2014 at 12:29 | comment | added | WhiteboxDev | @WaseemAli Yes, eq. 8 is equivalent to my first equation, i.e. the brackets are implied in the two-line form of the equation. You must perform the two subtractions before the division. Nonetheless, you still could not use this equation and get values in the range -0.63 to -0.001. Either your min and max values are incorrect or your usage of the equation was incorrect. I'd just double check both and see where you went wrong. These kinds of mistakes happen all the time during an analysis ;) | |
| Oct 22, 2014 at 11:30 | comment | added | Joseph | Very nicely detailed answer! I'm always surprised to see what various analytics can be applied to rasters. | |
| Oct 22, 2014 at 4:52 | comment | added | Waseem Ali | I am following the research paper link_itlic_ bold 'code' and equatin 8 and want to make the graph as in figure 4 in this paper. | |
| Oct 21, 2014 at 23:18 | history | edited | WhiteboxDev | CC BY-SA 3.0 |
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| Oct 21, 2014 at 22:52 | history | edited | WhiteboxDev | CC BY-SA 3.0 |
added 88 characters in body
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| Oct 21, 2014 at 22:46 | history | answered | WhiteboxDev | CC BY-SA 3.0 |