Questions tagged [digital-image-processing]

The field of raster image processing

15
votes
2answers
767 views

completing satellite imagery tiles when data coverage is less than 100%

I want to join several images (>=2) into one "best" image. Best is defined on low cloud cover and high data coverage. An example using free Sentinel satelite data follows. See http://sentinel-s2-...
-1
votes
1answer
348 views

Find maximum of large (size) multiple rasters

I have several large rasters (300MB - 1GB), each raster has been reclassified with numpy array and GDAL blocks. I now need to create an output file with only the maximum value per pixel used in the ...
1
vote
1answer
198 views

How to convert NoData values to other values for raster data?

I have a NDVI map from MODIS data for my AOI. When classified, i noticed that few of the pixels appear in " white" color and show no value. How do i classify these pixels and attache an appropriate / ...
0
votes
1answer
85 views

Classifying concrete material through greyscale in ArcGIS Desktop?

I get greyscale image successfully , but I have some query about pixel value classification, because concrete have cement,fine and coarse aggregate. How can I classify this material through greyscale? ...
1
vote
2answers
632 views

Calculate NDVI image from R and NIR channels and rescale it to 0-255

I have images of plants taken in Red(R) and Near End Infrared(NIR) field, I calculate the NDVI image per pixel using the below formula, NDVI = (R-NIR)/(R+NIR) , for all pixels, I get a range ...
1
vote
0answers
58 views

Make Chessboard stack Image

I am learning some literature of works and came across a beautiful representation of image in chessboard form. That misaligned is not my current concern. We are group of bachelor students and are ...
8
votes
0answers
311 views

Executing bidirectional dijkstra on TIFF image?

Can anyone indicate an example of how to do this? Link, tutorial etc... I started a discussion here about how to load a TIFF image like a graph nicely answered by @sehe. But, in this post the image is ...
1
vote
0answers
245 views

How to perform accuracy assessment in eCognition?

I have already done the classification using Nearest neighbourhood, and how do I continue to complete AC with TAA?
0
votes
1answer
70 views

Detection of avalanche debris based on their distinctive shape

I want to detect avalanche debris of a known avalanche using Sentinel-2 optical imagery. I've calculated the Normalized Difference Snow Index and from there I've extracted all the values above 0.4 ...
3
votes
0answers
793 views

Using WATERSHED to delineate tree crowns in ArcGIS Desktop? [closed]

I'm trying to delineate and count trees from a DSM/DTM generated from a UAV survey. It's from a citrus grove where trees are growing in different spacing. I have developed a workflow that works for ...
5
votes
2answers
425 views

Calibrating Landsat Level-1 Precision and Terrain (L1TP) corrected data?

My study will involve Landsat OLI, ETM+ and TM scenes for forest biomass change assessment (Time Series Analysis) using different vegetation indices and textures. According to the official site https:/...
0
votes
1answer
338 views

Calculating band depth image for M3 data

I am working with chandrayaan M3 hyper spectral data. I need to create a band depth image for identifying mineral abundances. How do i calculate the continuum reflectance value for producing a band ...
0
votes
1answer
270 views

Preparing an integrated band depth image

How do i prepare an integrated band depth image? If i have to prepare an 1 micrometer integrated band depth image (sum of 0.79 and 1.3 band depth micrometer bands), do i just average all bands from ...
0
votes
1answer
179 views

Why is ArcPy script looping through bands slow?

I am working on a single tiff with over 20k bands, each representing daily temperature, and I'll be extracting and preforming simple raster math on roughly 3500 of the bands. The problem I'm running ...
1
vote
0answers
516 views

What causes this rainbow image artifact in Google Maps satellite imagery?

I discovered this "rainbow" over the Yellowstone River in Google Maps: View the site in Google Maps: https://goo.gl/maps/y6xETmY859M2 You can see a distinct red, yellow, and blue streak hovering ...
1
vote
1answer
440 views

How to save an image stretch/enhancement in ENVI?

I am using ENVI 5.3.1 and viewing a georeferenced satellite image with a linear 1% histogram stretch applied to the entire image. When exporting the image with the current histogram stretch using File-...
1
vote
1answer
104 views

R Script for Computing Image Means and Raster Value Subtractions

I have a very specific script I am trying to make which computes image flatfields. Basically, I am computing a Master Dark Frame (MD) by averaging a set of Dark Photos. I have a set of light photos ...
1
vote
2answers
3k views

Supervised image classification in QGIS

Is it possible to do supervised image classification in QGIS? I require it for the estimation of cover management factor (C factor) in USLE
2
votes
2answers
182 views

Dot density map “slicing” dots when exported

I'm running ArcMap 10.3 and every time I export a dot density map it "slices" long, horizontal gashes in sections of the dots (see screenshot below). The cuts are never vertical, always horizontal, ...
11
votes
2answers
771 views

Is it scientifically correct to pansharpen landsat reflectance product with pan band

I need to know if it is scientifically valid to fuse/pan-sharpen Landsat 8 surface reflectance products with pan band of that respective band? Landsat reflectance product details can be found at here. ...
1
vote
1answer
131 views

Atmospheric correction of Landsat 7 slc-off images

I am interested in finding the change in land cover particularly forests. I am working with slc-off images (no other sensor images available for my study). I have done the gap-filling in Erdas Imagine ...
1
vote
0answers
25 views

Ingest 8-band satellite imagery into an array in C?

I’ve been unable to locate a lightweight library implemented in C to ingest 8-band geotiff files. GDAL can do this easily in python, though I’ve been unable to get the GDAL C libraries working; I’ve ...
3
votes
0answers
467 views

Remove near black borders on Landsat 8 overview images

I want to eliminate near black pixels around edges of Landsat-8 overview. I'm interested in doing it not for the entire image but some extent, so I clipped it. I tried using GDAL nearblack utility, ...
0
votes
1answer
673 views

Satellite image stretch with python: skimage, numpy

I am trying to perform a simple contrast stretch with python skimage on the image opened with gdal as array of type float32. I first calculate the percentile with: p2, p98 = np.percentile(arrayF, (P1,...
0
votes
1answer
1k views

How to find out Actual coordinate(pixel values) of chunk relative to the actual image?

I have an image of let say 500 X 500 px, I created tiles/chunks of size (10, 10). Now I want to find out actual chunk coordinate relative to the Original 500X500 px image. Ex I have first chunk of ...
0
votes
2answers
300 views

Validation points for supervise classification

I have undertaken supervised classification (maximum likelihood) and planning to survey the ground to validate the output. How many validation points do I need to take? The raster is a landsat tile ...
1
vote
0answers
7k views

Zero-size array to reduction operation maximum which has no identity

Below is my identify background code, which identifies a background from an image and removes it.; Previously it's was working fine but after I chunked my images and try to find out background I got ...
12
votes
4answers
9k views

How to split a .tif image into several tiles?

I have an image of size 1GB (.tif), with the width and height 94000x71680. I would like to chunk this image into 20000X20000 tiles so that I can process them. How can I do this?
0
votes
1answer
369 views

How to Find Local Lowest Point(s) on a Landform?

I am trying to write a code to find the local lowest points using Python. This approach will be applied to raster landform data such as digital elevation models. What approach can I take to find the ...
1
vote
0answers
61 views

Corrupted Image Layer of DPR File (eCognition Project)

I just started working with eCognition a few months ago and it is my first time to encounter a problem. I was on the refinement stage (and almost done manual brushing objects) when I found out that ...
1
vote
1answer
118 views

Plotting Vector data on Raster Map

I have a Raster map with East,West, North and south boundaries as follows (-118.875,-118.75,37.125, 37) and a Vector data. Now I want to plot a vector lines on this raster map. the vector line is in ...
0
votes
2answers
2k views

Auto digitizing features on map? [duplicate]

I'm new to digitization. I have the following map and I'm trying to digitize the purple features. Is there any way to automatically digitize all the purple lines on the map.
2
votes
2answers
520 views

Nearest Neighbour Classification in eCognition

I have a few papers and youtube videos explaining how to conduct the NN classification in eCognition but it isnt giving me any output. I think the confusion is arising when trying to define the ...
1
vote
1answer
517 views

Loop over GeoTIFF image pixels, extract coordinates and pixel color

I have a very large GeoTIFF image (~650MB) with color-coded landcover data from here. I need to extract the latitude, longitude, and pixel color for each pixel in the image, so I can import it into a ...
2
votes
0answers
55 views

Finding pre-processed MODIS products?

I am trying to recognize burnt areas based on some MODIS products and I just realized that I am missing a bunch pixels from the coastline masking. As you can understand that is an issue because I am ...
1
vote
1answer
327 views

How to extract MODIS QA informaton

I want to use the LDOPE tool unpack_sds_bits to extract the bit information from the State QA layer of the MYD09GA Aqua Surface Reflectance product. However, I have never run a command line before ...
1
vote
0answers
61 views

Find densest point in satellite agriculture map [closed]

I have a .tiff image file with 3 bands. I want to write a program, (python opencv?), that will find the first N densest points in the region. Densest, meaning the point with the most of its own ...
5
votes
2answers
315 views

Pattern search in satellite imagery

I would like to search for the specific buildings (polyhouse in my case) on the map like the one shown here Are there any free options available which can give me lat and lng of such shapes/features ...
1
vote
1answer
775 views

Combining hyperspectral bands to form a multispectral image?

I understand that the difference between the two are the number and width of the bands. Given a hyperspectral image, is it possible to 'convert' it to multispectral ? In this paper for example, the ...
2
votes
1answer
71 views

Aerial picture - how can I extract water drainages on a crop (to vectorize them)

I have a RGB aerial picture of an agricultural crop. The drainages (hundreds of them) can be barely seen because they a very slightly greener then the surrounding crop area (picture is from April). ...
1
vote
0answers
620 views

How to convert .HDF to .Tiff and keep the number of the output files exactly as the input?

I have 332 .HDF files that I have processed in R to convert them to .Tiff. It has worked fine, however, the number of output files are not the same as the number of the input files! Input is 332, ...
2
votes
3answers
2k views

What preprocessing is required when using Landsat for LULC?

Can anyone help me regarding the what kind of image pre-processing techniques should be used for the landsat images downloaded from http://earthexplorer.usgs.gov/ to create land-use land-cover (LULC) ...
3
votes
2answers
154 views

Pansharpening influence on analysis

Using as an example Landsat 8 bands: Does pansharpening band enhace only visible range and therefore can I use it only for analysis connected with visible spectrum? Or I can pansharpen every possible ...
12
votes
2answers
315 views

Ice type differentiation using satellite data

I would like to classify glacial area by categories of snow (if there is) and ice, but what's most important: between old ice and fresh ice. They have different properties that are possible to ...
3
votes
2answers
525 views

Looking for real-world DJI Phantom 3 Professional sample geo-tagged images for testing

I am looking for sample DJI Phantom 3 Professional imagery for testing purposes with the Drone2Map for ArcGIS Beta software. So far I am finding the application very polished and easy to use but I am ...
1
vote
1answer
651 views

Make Image Pyramid from JP2 Raster

I have ~1.7 GB JP2 Buckeye that I want to serve out from Geoserver; I'd like to have it tiled so that the client won't have to redraw everytime they zoom into the map. My current understanding is that ...
1
vote
1answer
538 views

How to define a threshold in Principal Component Image for Urban mapping?

I am working on an Urban mapping and i would like to know how i could define a threshold value for extracting built-up areas from a PC (Principal Component) Image ? I am interesting on how to ...
2
votes
2answers
154 views

Installing pre-requisites for forest classification using SCP and QGIS?

I am using QGIS 2.8.6 and I want to use SCP for forest classification from Landsat 8 oli. I have already installed the SPP plugin. What else do I need to install for operation of the software?
3
votes
1answer
62 views

Globbing in Windows to process images - how do bash loops look in DOS?

I'm doing some batch image processing with imagemagick on OSX using this line: for file in $(cat all.txt); do convert -crop 50X50@ +repage +adjoin "$file" "$file"_tile_50x50@_%d.jpeg; done It takes ...
1
vote
0answers
67 views

i.spectral tool error

system description: Windows7 32 bıt OS, Grass GIS 7.0.0 Gnuplot 5.0 Solution attempt 01: On the basis of following thread, commented out said path check lines from i.spectral.py script: https://...