23
votes
Accepted
Reading, modifying and writing a geotiff with GDAL in python
Your script is missing the ds.FlushCache method, that saves to disk what you have in memory at the end of the modifications. See below a corrected version of your example. Notice that I also added two ...
- 675
14
votes
Accepted
Is the reflectance required to get the NDVI, for Landsat 8 images?
NDVI is defined for any two bands with near-infrared and infrared data (it is an empirical remote sensing index). As such, you can calculate it straight from the DNs. This is mostly OK if you are only ...
- 1,234
13
votes
Accepted
LS7 filling the gaps image with Google Earth Engine
You could try filling the gaps before you aggregate them by month.
USGS published a LS7 SLC-off gap-filling algorithm.
This algorithm was recreated for Google Earth Engine by Noel Gorelick: https://...
- 9,500
13
votes
Writing code for monthly NDVI medians in Google Earth Engine?
For the record, here is a good way to do this:
var imageCollection = ee.ImageCollection("LANDSAT/LT05/C01/T1");
var months = ee.List.sequence(1, 12);
var composites = ee.ImageCollection.fromImages(...
- 4,054
12
votes
Accepted
Importing multiple stacked raster images in R?
Have a look at nlayers(s). The returned number of layers will equal 28 - at least for the above example with 4 multi-layer objects encompassing 7 layers each. Applying stack to multiple multi-layer ...
- 5,063
12
votes
Filtering Landsat images base on cloud cover over region of interest
It's going to be something like this, but you'll need to play with the threshold (10 in this example) to meet your needs. Watch out for ROIs that overlap a scene's footprint, but do not contain any ...
- 4,054
10
votes
Accepted
Landsat images with bad quality
The Scan Line Corrector in the ETM+ instrument onboard Landsat-7 suffered a (suspected) mechanical failure in 2003, so all subsequent images suffer from the striping you are seeing in your images. The ...
- 10.6k
9
votes
Methodology for Hansen classification of Global Forest Watch?
The Supplementary Materials (SM) for the Science article provides references to a number of different journal-articles that outline various parts of the methodology.
The SM can be found here
...
- 6,396
9
votes
Accepted
Remote Sensing Landsat Surface Reflectance and Albedo
The Landsat reflectance data you downloaded from USGS has been scaled using a scale factor of 0.0001. So multiplying the digital number by 0.0001 will give you a value between 0 and 1. The 2000 value ...
- 669
8
votes
Tutorial Vegetation Condition Index
Kogan (2004) (p. 2891) provides the following formula for the Vegetation Condition Index (VCI):
VCI = 100 * (NDVI - NDVImin) / (NDVImax - NDVImin)
where,
NDVI = Smoothed weekly NDVI value
NDVImin ...
- 50.4k
8
votes
Accepted
Error installing landsat-util on Linux
gnutls.h which is required is missing from the filesystem even if you install libcurl4-gnutls-dev which supposedly has the headers files for curl.
to correct for that error run:
# apt-get install ...
- 11.1k
8
votes
Why Landsat ETM+ panchromatic band' wavelength steps over visible range?
A major reason for having panchromatic bands covering a broad spectral range is a technical reason: most of the solar energy reflected by the Earth is in the NIR wavelength. As the aim of a single ...
- 48.7k
8
votes
Add bands' name and description to the Metadata when stacking using rasterio
If using rasterio >= 1.0, use the dataset.set_band_description(self, bidx, value) method and dataset.descriptions property.
Sets the description of a dataset band.
Parameters
----------
bidx : int
...
- 53.3k
8
votes
Accepted
Noisy lines in all scenes for Landsat 7?
You should read about the Landsat 7 ETM+ SLC-off data
This refers to all Landsat 7 images collected after May 31, 2003, when the Scan Line Corrector (SLC) failed. These products have data gaps, but ...
- 2,600
7
votes
Accepted
Best Landsat-5 TM band combination for detecting fire scars
This varies greatly on the characteristics of the scene. Fire scar mapping studies using Landsat-5 TM have used the following three band combinations:
Spain: Bands 4, 5, 7
CHUVIECO, E., and ...
- 50.4k
7
votes
Extract elevation data from Landsat / MODIS imagery?
Landsat and Modis are optical sensors, which means that they provide digital numbers of reflected materials that are within the electromagnetic spectrum. These values correspond to the wave length of ...
- 9,253
7
votes
Calibrating Landsat Level-1 Precision and Terrain (L1TP) corrected data?
The three sensors are all slightly different. However the OLI/TIRs setup is a marked departure from the TM/ETM+ sensors. The changes are succintly summarised by Li et al. 2013 as the:
replacing of ...
- 2,036
7
votes
Accepted
Why Landsat ETM+ panchromatic band' wavelength steps over visible range?
A brief explanation can be found in the pdf file 'Landsat 8 (L8) Data Users Handbook', available from landsat.usgs.gov.
On page 9, first paragraph, it is said:
The OLI panchromatic band, Band 8, ...
- 9,911
7
votes
Accepted
Apply cloud mask to Landsat Imagery in Google Earth Engine Python API
for i in range(start,end-1): should be for i in range(start,end+1):
Tested it, and your code works fine.
- 9,316
7
votes
Accepted
Using cloud confidence to create cloud mask from Landsat 8 BQA?
Here is a more flexible approach that can handle dual (or larger) bit patterns. The bit shifts are performed server-side, using the ee.Image.rightShift() and ee.Image.mod() methods.
var RADIX = 2; //...
- 4,851
6
votes
automatically geo- and ortho- rectify raw Landsat data using DEM
Answer for others so confused people as I am:
To know how to deal with downloaded raw Landsat data - what else in pre-processing do I need?
Firstly check their processing level in_MTL.txt file (...
- 3,276
6
votes
Accepted
Methodology for Hansen classification of Global Forest Watch?
Matt Hansen's team has a paper published on forest cover change in Eastern Europe that goes back to 1985 - see Eastern Europe's forest cover dynamics from 1985 to 2012 quantified from the full Landsat ...
- 76
6
votes
Accepted
Save rasters created by loop operation to different directory?
This is almost a duplicate of this post, but you have an additional cropping step, so I'll post a new solution.
Given your .img files all have identical extent and resolution, you can save a lot of ...
- 747
6
votes
Accepted
Verifying landsat reflectance values?
Your question is two-fold.
With regards to the actual atmospherically corrected data: there is no simple method for testing if the calculated reflectance values are right. However, the simplest ...
- 6,396
6
votes
Confidence in pan-sharpened classification?
In general, there are two approaches to classification: pixel-based and object-based:
Pixel-based: Each spatial pixel is evaluated by itself against a set classification parameters. In this case, ...
- 6,396
6
votes
Accepted
Is atmospheric correction necessary when working with multi-spectral indexes?
It depends upon the intended use of the Landsat data. Generally speaking, if you are doing multi-temporal analyses, you need atmospherically corrected data, otherwise DN format is sufficient. I would ...
- 50.4k
6
votes
Accepted
Classify forest with NDVI from Landsat 8 and 7
No, the NDVI threshold value will not be the same for the time series due to differences in phenology and unique conditions on the ground. As Kersten mentioned in the comments, you may want to ...
- 50.4k
6
votes
Pan sharpening of SPOT and Landsat images
Pan sharpening is a well documented image processing technique and you will find bunch of HowTo's and tools in the web (GDAL, ArcGIS, Orfeo TB, Grass, ENVI).
On a common data oriented processing ...
- 3,483
6
votes
Accepted
Difference between Landsat 7 and Landsat 8 TOA reflectance computation
The two products are comparable with some initial considerations. As you can see, the resolutions of the products are more or less the same:
To give a more visual comparison of the spectral bands ...
- 4,438
6
votes
Landsat 5, 7, and 8 surface reflectance Tasseled cap
I have found these Tasseled Cap coefficients for use with Landsat Surface reflectance data.
Please refer to the source article for applicability to your work.
http://journals.plos.org/plosone/article?...
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