Questions tagged [ndvi]

Normalized Difference Vegetation Index is used to quickly identify vegetation and its condition in remotely-sensed data.

Filter by
Sorted by
Tagged with
2
votes
1answer
2k views

Using Loop for calculating NDVI in R?

I am using MOD09Q1 now and I would like to calculating NDVI whole year data. One year, I have 46 band 1 images and 46 band 2 images. list.files I creating list of band 1 and list of band 2. ...
1
vote
1answer
185 views

how to calculate the ndvi % greater than 0.5 in a particular zone and also cloud percentage

i have a problem whem i am working to calculate the ndvi from landsat sattellite of rainy season i have assumed the pixel value above 15000 are clouds and calculate NDVI.then i am assigning the clouds ...
2
votes
1answer
513 views

Failure in TIMESAT integral calculation

in short: My TIMESAT image-output of the seasonal parameter “Large Seasonal Integral” is wrong. TIMESAT continues to write a file with negative values (as 16 byte Integer) although Parameters should ...
3
votes
1answer
296 views

Determining the best month for discriminating between different vegetation types?

I ordered and downloaded several (Surface Reflectance) Landsat 5-8 images from USGS Earth Explorer with the purpose of choosing a few of them to calculate some Vegetation Indices for each (NDVI, SAVI, ...
0
votes
1answer
318 views

Why do pixel (cell) values change for 32 real NDVI values when taking from Multispec to QGIS?

Landsat 5 values change from normal NDVI -1 to 1 when created in Multispec as a 32 bit signed data image. When adding the raster layer in QGIS, the value range changed to 0-255. How does one ...
0
votes
2answers
992 views

Landsat8 NDVI values not in the -1 to 1 range

I was trying to create an NDVI from Landsat8 OLI image from July 2013. I ran DOS1 and TOA. The values range up to 3. The original files were downloaded from EarthExplorer(EE), ran on QGIS and ...
4
votes
2answers
5k views

Standard color mapping for NDVI?

I am currently generating some NDVI imagery using QGIS 2.8.2 and there are a multitude of possible color map scales that can be applied to the imagery. I was wondering if there was a preferred or ...
1
vote
1answer
288 views

NDVI error in ERDAS

I have created a NDVI image from Landsat 7 data using ERDAS (veg_NDVI.gmd). This model was already in ERDAS 9.3. After creation the final output visually highlighting vegetative areas but the value ...
3
votes
1answer
2k views

Is atmospheric correction necessary when working with multi-spectral indexes?

When you are working with Landsat Level 1 data and calculate indexes, e.g. NDVI, NDBI, SAVI ..., do you calculate them using raw data (pixel DN value), or atmospherically corrected data (surface ...
3
votes
2answers
206 views

Estimating Area of farm under cultivation using NDVI?

I have shapefiles for more than 1000 farms. I want to use Hydrological model to model the water balance in these farms. Each farm is devided in to seperate parts . My problem is that the whole ...
1
vote
0answers
665 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 ...
2
votes
2answers
574 views

NDVI from Landsat8 LandsatLook images

I have downloaded landsat image from this site and now Im wondering if i can get NDVI index from it. In raster calculator I have only 3 ranges, shouldnt be four? Or am I doing something wrong? If ...
1
vote
0answers
42 views

Making virtual raster with average values [duplicate]

I'm working with many raster files. Is there a way to make virtual raster with average values in each pixel. (QGIS) It's for an NDVI index of summer months over 5 years.
1
vote
2answers
813 views

Splitting picture taken with regular digital camera into real spectral RGB channels?

I have no idea how the sensors inside a camera work. I know I can take jpeg and separate the R, G and B channels but I have no idea whether these channels are the real red, blue and green in visible ...
0
votes
4answers
4k views

Free download NDVI images or raw satellite images for Sri Lanka?

Could anyone provide a site to download NDVI images or raw satellite images of Sri Lanka (Asia) for free for me to calculate the NDVI.
1
vote
0answers
79 views

Using NDVI values as covariate in survival analyses

I am trying to become more familiar with processing NDVI values in GIS. However, despite its usefulness, it seems to have some limitations. Namely, creating NDVI values across a large scale can be ...
0
votes
0answers
89 views

Looping over array of type float with interval of float (NDVI) using Python?

I am stuck with my Python Script. The case is, I have an array of floating numbers from 0 to 1 (NDVI values). I want to loop over my array with an interval/step of every 0.025. Every interval/step I ...
1
vote
1answer
543 views

Doing NDVI when nir data is given as 3 bands

I have been provided with two data sets of the same area, one with normal RGB bands and one with NIR data. My problem is that since the NIR data is given as 3 bands, i am not sure how I should ...
0
votes
1answer
94 views

NDVI for natural region

I have remote sensing data which I have got from landsat 7. The area which I am working on is combination of farms and natural area (Bare earth; without any vegetation). I want to estimate the ...
4
votes
4answers
3k views

Where to download 4-band NAIP imagery for California?

I've been trying to find orthoimages with 4 bands for a couple of counties in California. I managed to download some from the GeoSpatial Data Gateway from the USDA (NRCS), but they all only have 3 ...
1
vote
1answer
3k views

EVI and NDVI range value

I've used a Landsat 8 image for vegetation analysis in an urban area. I've got a large maximum number of EVI value as shown in this image: Is this normal in calculating EVI and NDVI? Because I know ...
4
votes
1answer
4k views

Calculating NDVI with Rasterio

I'm using Rasterio to read GeoTIFF files from Landsat 8 and calculate NDVI into a new GeoTIFF file. My code looks like this: import numpy import rasterio import subprocess with rasterio.drivers(...
3
votes
1answer
823 views

Applying savitzky golay filter to MODIS NDVI data

I want to smooth the NDVI MODIS 16 bit integer data .tif for LULC classification. I have timesat 3.1 software on windows but I don't how to apply the SG filter. I am not that good in programming. I ...
0
votes
2answers
158 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 ...
1
vote
3answers
361 views

Analysis MODIS NDVI - MOD12A2

I am trying to analyse the images that I downloaded from MODIS, which are the Vegetation Indices 16-Day L3 Global 1km. With this data I want to analyse the change in vegetation over the years in a ...
1
vote
0answers
83 views

problem with running raster calculator in grassgis

When I was trying to do NDVI with grassGIS I faced a problem. I cannot run the raster calculation. When I looked to the command console I see that (Sat Feb 21 12:41:58 2015) r.mapcalc ddes = ( ...
0
votes
2answers
150 views

NDVI Web services over Victoria australia

Does anyone know of any web services that are available where you can pass...say a WKT polygon or point and return the mean NDVI or NDVI from that point from an array of the most recent NDVI runs?
1
vote
2answers
1k views

How to create an image of mean values from multiple NDVI images?

I have downloaded MODIS NDVI images of 12 months. I would like to create just 1 image with the mean values. I tried using IDRISI's 'NDVI compositing utility', but I get an error. Is there a way to do ...
5
votes
1answer
6k views

NDVI from ESA's Sentinel-2 training data

I'am trying to generate an NDVI map using ESA's Sentinel-2 training images, which can be found at https://spot-take5.org. I tried using QGIS's raster calculator to create the NDVI image, however quite ...
2
votes
1answer
972 views

How to interpret Tasseled Cap Greenness for Landsat 5?

I have amassed a few promising literature articles, and looked at the help files for ENVI, ArcMap and PCI, and no one really goes into great depth on how to interpret spectral values for Tasseled Cap ...
1
vote
1answer
3k views

Generating NDVI with multi channel images?

I have a 6 channel proprietary camera and I need to create a NDVI map. I created a map from each band, so now I have 6 files each one on a different band width. How can I proceed now using QGIS?
3
votes
0answers
109 views

VI Quality dataset in MODIS image [closed]

While importing NDVI dataset in ArcGIS should we also import the VI_Quality dataset ? If yes then how should we handle it ? and, if not, then for what it is there ?
4
votes
2answers
1k views

Classification, Change detection and NDVI Using (landsat2 MSS), (landsat5 TM), (Landsat7 ETM+) and (Landsat8 OLI)

I have 5 Landsat images for the same study area. One of them in 1975 (Landsat 2 MSS), two in 1985 and 1995 (Landsat 5 TM) and one in 2005 (Landsat 7 ETM+) and the last one in 2014 (Landsat8 OLI). I ...
0
votes
1answer
659 views

Analyzing stacked time series NDVI images in ENVI

I just started playing around with stacking NDVI images from different years into one RGB value and am unsure how to read the photos or analyze them. The image on the left had R 2011 G 2011 and B ...
-1
votes
1answer
1k views

Calculating average NDVI

I would like to calculate average NDVI values. I have 3 values of NDVI: high:243 low:0 high:243 low:0 high:238 low:0 How can I use a a raster calculator to calculate the average valvue
2
votes
1answer
2k views

How to create NDVI map From LiDAR intensity and RGB image

I am new with GIS and I've been looking for ways on how I could create a NDVI map from LiDAR intensity and RGB image. Is there any way I could do this? I have read that you could create an intensity ...
1
vote
1answer
77 views

Long term NDVI mean from different resolution satellite imageries

I have 10 years satellite imageries of different resolution (Landsat TM, LISS3, AWiFS and Landsat 8). My aim is to generate long term mean NDVI from that data. Since the resolutions are not same, i ...
-1
votes
2answers
2k views

How to calculate average NDVI values for buffers in ArcGIS?

I would need to calculate an average NDVI value for each buffer among everal hundred buffer-areas. The buffer areas are built around observation points. I have all buffer areas in one .shp file and ...
0
votes
1answer
639 views

How to conduct an NDVI and regression with ArcMap?

I would ideally like to execute an NDVI on a sample of NAIP images and then use the NDVI scores per district or whatever my aggregate zone is, probably census tract. My goal is to identify census ...
1
vote
2answers
2k views

Classification, change detection and NDVI using landsat 2 (MSS), landsat 5 (TM) and Landsat 7 (ETM)

I have 3 Landsat images for the same area. One in 1972 (landsat 2 mss), one in 1996 (landsat 5 TM) and one in 2010 (landsat 7 ETM). I would like to detect changes in land cover and create diachronic ...
0
votes
2answers
1k views

Normalize the NDVI raster 0-255

NDVI values raster computed by using the band 3 and band 4 reflectance values b4-b3/b4+b3. The output raster is of 32bit type formate although the possible ranges that shows in statistics parameter ...
2
votes
0answers
400 views

QGIS 2.4.0-Chugiak: How to produce raster colour map

By carefully deriving the NDVI values from Landsat Band 3 and Band 4 after doing atmospheric correction by applying DOS1 method in semi-automatic classification Plugin QGIS, I was to calculate the ...
2
votes
2answers
1k views

NDVI derived from Landsat band 3 and band 4 using QGIS raster calculator shows the different range when opening in the ArcGIS

I have calculated Normalized difference vegetation indices from landsat 5 band 3 and band 4 that have 0-0.38 minimum and maximum ranges respectively. But whenever I open the same NDVI.tiff file in ...
4
votes
3answers
2k views

How can I identify types of crops in agricultural raster dataset?

I have some 2014 MrSID files from the National Agricultural Imagery Program (NAIP) that I've converted to TIFF files. I want to use them to find the area of tomato farms in a watershed. I'm using ...
1
vote
0answers
875 views

Fitting Time-series Values with a Gaussian Function

I'm trying to fit a stack of NDVI values to a Gaussian model to allow for determining dates of certain NDVI values using Python and NumPy/SciPy. I've attempted to do this with scipy.optimize.curve_fit....
2
votes
1answer
592 views

Calculating quantile values over a stack of images with grass gis. Help needed on r.series

I need to calculate the values for the 25%, 50%, 75% and 90% quantile over a series of rasters (time series of ndvi values from landsat). I am exploring the r.series command in Grass GIS, but the ...
3
votes
2answers
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'...
2
votes
1answer
1k views

ListRasters based on filename using Arcpy

I am trying to create a python script for ArcMap which calculates the ndvi from two raster images for each RGB/NIR pair in a folder. However, I am unsure how to create two raster lists; one which ...
1
vote
1answer
251 views

Apply regression equation to Landsat ETM+ image

I have sample points in an Excel file with XY coordinates and canopy density. I also have a Landsat ETM+ image. All points are collected from the same area as in the image. I exported all sample ...
1
vote
1answer
311 views

Canopy density & NDVI Regression using ArcGIS for Desktop?

I have a Landsat ETM+ image, I also have 200 sample points with coordinates,canopy density, different band values and NDVI values. If I build OLS model I only got sample points regressed. How can I ...