All Questions
16 questions
1
vote
1
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57
views
Direct use of Sentinel 2 L2A imagery for vegetation analysis
I am working on my research to calculate the green vegetation in the study area using sentinel 2 L2A 10m resolution. Do I need to perform any correction or smoothing before analysis?
- 13
0
votes
0
answers
188
views
Why do I get wrong NDVI, EVI values in crop monitoring?
I have been monitoring agriculture lands with Sentinel-2 S2MSI2A data. I'm calculating NDVI and EVI for the vegetation. The NDVI values are slowly increasing because the growing crops which is look ...
- 21
1
vote
1
answer
730
views
Landsat level-2 NDVI valid range with saturation
I have Landsat level-2 NDVI tiles I am using in ArcMap 10.4.1.; however, the level-2 NDVI data in ArcMap ranges from -5,189 to +20,000.
The spectral image product guide (which I've linked) says that ...
- 425
4
votes
1
answer
742
views
Why getting wrong NDVI values resulted from scaled reflectance in ArcMap?
I have made atmospheric corrections to my Landsat 8-OLI raster using 'ENVI FLAASH' having surface reflectance values scaled between 1-100.
In ArcGIS I am using simple expression to compute NDVI ...
- 1,218
1
vote
1
answer
207
views
Cleaning up polygon generated from NDVI raster
So I have NDVI raster files for about 1000 acres of vineyards we manage. What I have done is created a model that takes the NDVi raster, reclassifies it to isolate out the areas of high vigor, then ...
- 31
1
vote
0
answers
58
views
Error when using Raster Calculator in ArcGIS to compute NDVI, Process output is binary, limited to pixels that are either 0 or -1 [duplicate]
I am using WorldView-3 satellite images that have been orthorectified and corrected to sensor reflectance values to compute a set of normalized difference indexes, including NDVI in ArcGIS version 10....
2
votes
1
answer
383
views
Why do UAV-derived NDVI values fall far outside -1 to 1 range after empirical line calibration?
This question was marked as being a duplicate of Landsat8 NDVI values not in the -1 to 1 range but I've posted my question because:
I am not using Landsat; and
there was no explanation of how to ...
- 61
1
vote
2
answers
1k
views
Using ArcGIS Raster Calculator to calculate MSAVI2 based on Landsat 8 OLI bands 4 and 5
I would like to calculate a Modified Soil-Adjusted Vegetation Index 2 on the basis of Landsat 8 OLI imagery, bands 5 (NIR) and 4 (RED), using the Raster Calculator. The formula should be:
I have ...
- 11
3
votes
1
answer
398
views
How to represent seasonal variability in a single global NDVI map?
I have twelve monthly MODIS datasets for a 1 year period (http://neo.sci.gsfc.nasa.gov/view.php?datasetId=MOD13A2_M_NDVI&year=2015) and wish to combine all the data into a single map highlighting ...
- 861
1
vote
0
answers
683
views
NDVI calculation using ArcGIS 10.1 [closed]
i have to derive NDVI from Landsat 8 image..
I used the following equation from landsat website with band 5 and band 4 using ArcGIS 10.1
Conversion to TOA Radiance
OLI and TIRS band data can be ...
- 11
0
votes
2
answers
190
views
AVHRR Max NDVI product
I'm trying to take a max annual NDVI product derived from AVHRR and relate it to a specific area that I'm examining.This requires me to identify the region of interest based on Landsat scenes, and ...
- 61
3
votes
2
answers
2k
views
Calculating NDVI using Landsat ETM+ band values
I have sample points (shape file converted from a .xls file which contains XY coordinates,nnx,nny and canopy density) and a landsat etm+ image. First I applied 'SpatialAnalyst Tools>Extraction >Sample'...
- 197
1
vote
1
answer
654
views
create a vegetation mask using Landsat 7 [closed]
I'm working on a very large study area. The aim is to create a vegetation mask representing only pines. I'm using Landsat 7 images. Since the recordings were made in the winter it's pretty easy to ...
- 292
3
votes
0
answers
3k
views
Interpreting NDVI value on water?
There is a surreal thing on my NDVI images. NDVI values on lake is ranging from -0.04 to 0.7. (The lake surrounded by forest and has freshwater). Theoretically, negative value of NDVI is correspond to ...
- 659
3
votes
3
answers
3k
views
NDVI image value changes from -1 to 1 in ENVI to 0-255 in ArcGIS Desktop and ERDAS Imagine?
When i open NDVI image in ENVI, its value is still within the range (-1 to 1).
But when I open this NDVI image in ERDAS and ArcGIS Desktop, its value is 0-255.
What does it mean?
Is the NDVI ...
- 31
3
votes
1
answer
484
views
Determining phenological events based on Greatest increase NDVI approach?
I have a problem with a phenological study. The study area is in temperate zone of Asia. I have been doing phenological research using MOD VI product. I wanted to extract phenological events (onset/...
- 169