Questions tagged [pixel]

In digital imaging, a pixel, or pel (picture element), is a single point in a raster image, or the smallest addressable screen element in a display device. In GIS applications, a pixel may also refer to an imagery layer or other raster data.

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35 views

Extract maximum pixel value vertex from a raster for a given grid cell without altering the position of the source location in QGIS

I have a 0.5 X 0.5 metre resolution raster. I would like to extract the maximum value points from the raster for every 2 metre square cell. And the extracted points should be in the centre of the ...
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3answers
33 views

Extracting pixel values in different bands for different points giving NAs and not pixel values

I am working with R statistics. And I am trying to extract pixel values for each point in each Landsat bands, however, I am just getting NAs instead of getting pixel values Does anyone have any ...
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15 views

Reprojection problem with Rasterio

I have already processed so far NDSI map by using Rrasterio, NumPy, os and matplotlib.pyplot for plotting the data. Now, I would like to eliminate permanent ice from NDSI map. I am facing one major ...
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1answer
517 views

Getting value of pixel and its 8 surrounding pixels from points using QGIS

I have a point Shapefile layer and a land cover raster layer. For each point, I want to get the value (land cover) of the pixel it falls into and also of the 8 surrounding pixel. Is there a tool in ...
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1answer
56 views

Explanation of reduce.count() function in Google Earth Engine

Following the indication on Calculating number of pixels in polygon using Google Earthy Engine? I wrote this script: var gfc =ee.Image('UMD/hansen/global_forest_change_2018_v1_6'); var lossyear = ...
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1answer
81 views

QGIS convert pixel location

Is it possible to convert a list of pixel locations (txt file) into lat long? What I have is: (left_x: 137 top_y: 146) (left_x: 175 top_y: 236) (left_x: 182 top_y: 153) (left_x: 185 ...
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1answer
206 views

QGIS 3.2 - Poor conversion from high-resolution vector to raster

I have a shapefile with polygons with several sizes, and I want to convert it to a raster with 30mx30m pixel resolution. Although I was able to obtain the raster with the pretended resolution (using ...
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0answers
25 views

Simultaneous raster downsampling/downscaling and upsampling/upscaling for false accuracy minimisation

I want to have a raster stack of two different resolutions. One is from VSNIR and one from SWIR sensors (hyperspectral). The VSNIR has a resolution of 25 cm and the SWIR of 80 cm and both data have ...
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1answer
477 views

Wrong Min and Max Pixel values

I want to convert a raster .tif file into a raster .asc file in QGIS. For this, I am selecting Raster -> Conversion -> Translate option. I am getting the output .asc file. But, both the minimum and ...
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1answer
107 views

Get pixel values from a raster using a multipartpolygon

I'm trying to get the mean value of pixels from an NDVI raster, that intersect the geometry of a FeatureCollection, that is a multipart polygon which represents my sample area, but I can't find the ...
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0answers
27 views

Convert pixels to coordinates

I have a vertical image with size (W,H). I have info about the coordinates in decimals of the the upper left and bottom right (Lat1,Lng1,Lat2,Lng2). I have the Ground Sample Distance (GSD) of the ...
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1answer
44 views

How to calculate mean pixels value of shapefile (for specific place)?

I have GeoTIFF image. I want to know how to calculate specific area mean pixels values? Is field calculator for(value*count fields) right or get raster properties? Or what can I do?
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No Data Value through Pixel Inspector in ArcMap

I have a raster that represents temperature on a global scale derived from satellite data. Initially it had pixels in the ocean assigned -9999. After I used SetNull tool to eliminate them they show up ...
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2answers
41 views

Get geographic coordinates based on pixel coordinates?

I'm working with Mask R-CNN to locate fires. I have the following image. I have info about the geographic center coordinates of the image, and the orientation of the image in degrees let's suppose ...
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1answer
264 views

Identifying pixels with sun glint in a satellite image (for atmospheric correction)

Wondering if anyone knows a way (perhaps objective) to identify pixels that are infected with sun glint in an image. I'm using Hedley's 2005 approach in a python to deglint my image but this approach ...
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1answer
35 views

Extracting pixel values for specific point locations in WGS 1984 / EPSG: 4326 image

I have a remote sensing image with GCS WGS 1984 / EPSG: 4326. I need to extract pixel values from this image which corresponds to specific point locations. For that purpose, I defined these ...
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1answer
74 views

Raster calculator - problems with syntax

I have a raster layer with values ranging from 0.00597303 to 0.102894 and I want to assign specific number representing a group to specific range of values: Group 4: x >= 0.1 Group 3: 0.01 <= x ...
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0answers
23 views

OpenLayers3 map.forEachLayerAtPixel bug

Hi I'm working with OpenLayers version 3 and using method map.forEachLayerAtPixel(). The problem is I usually work on big screen and now I have switched to my laptop with smaller one and suddenly ...
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2answers
48 views

Selecting all the pixels in a raster coverage that have a specific pixel value? (in PostGIS raster)

I have a land use map in the format of TIFF. I imported this file as a table in PostGIS using raster2pgsql. The land use file has 7 different classes. How can I select all those pixels that have the ...
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1answer
179 views

Getting coordinates of pixel from georeferenced drone photo?

I have a problem with geo-referenced photos from a DJI drone. I have the coordinates of the center of the photo and the metadata related to the photo and I would like to know how to go from a pixel to ...
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3answers
873 views

Can single raster pixel hold more than one value?

Can a single pixel of a raster hold more than one value?
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1answer
46 views

Updating raster pixel values where they overlap with another raster band

I am trying to replace/update the raster pixel values of band '3' of a Land Cover Map to a new value of '24', but only where these pixels overlap with value '4' of another raster layer. How do I write ...
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0answers
25 views

Getting stripe across tiles without buffering image?

I am new to geotools. I need to get a horizontal stripe of bytes from the image data without buffering the whole image. I've looked at the various envelopes and pretty sure I could use just ...
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1answer
129 views

Calculating the distance of each pixel in a raster from a point in PostGIS [closed]

I have a raster in PostGIS and a table of points. I want to calculate the distance of each pixel to each point. How can I do that? For example, if 9 pixels and 3 points, then I want to calculate 27 ...
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1answer
100 views

How to write a single pixel or a line of pixels to GeoTIFF using GDAL/Python

Let's say I want to write a single pixel or a 1D array of pixels (e.g.all at the same latitude) of pixels to a single-band of a Float32 GeoTIFF using the Python GDAL bindings. How can I do so? Or is ...
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2answers
56 views

Cannot read pixel value from DTM raster with QGIS

I am using this DTM: http://ags.cuzk.cz/arcgis2/services/dmr4g/ImageServer/WMSServer?request=GetCapabilities&service=WMS At ArcGIS I am able to ready pixel value of the raster but at QGIS it ...
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3answers
153 views

Converting raster pixels to vector cells?

Is there any way to convert raster pixels to vector cells? I mean each pixel to a polygon. I tried the SAGA tool 'Raster values to points' by choosing cells option instead of nodes option. As a ...
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0answers
35 views

delete pixels intersecting vector border

I have a two files : vector file : polygon (red) raster file : got by clipping a raster file using this vector file (Green) I want to delete pixels that intersect with the vector border (I want to ...
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1answer
71 views

Wrong masked pixels

I am new in GEE, and tried to run a simple code to mask cloud pixels. However when I added the image selected with my filters I saw that the result of the cloud filter are empty areas, as shown below: ...
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0answers
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Is there a way to interpolate lost data/lost pixels caused by cloud and cloud shadow masks in Google Earth Engine? [duplicate]

I'm sure cloud and cloud shadows have been, time and time again, a frustrating problem. Usually after masking the two, I composite multiple images (in a set time interval e.g. 2015-2016, months 6-8) ...
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1answer
46 views

Obtaining pixels between 2 raster layers (border)?

I have a rasterStack obtained from a stack of 3 raster layers by: image = stack(A, B, C) I would like to calculate the distance between the pixels of layer A and pixels of layer C. After ...
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1answer
48 views

Can I change the pixel sizes in a world file?

I start with a dataset that has projection WGS84 and pixel size 0.000274658203125 degrees/pixel. I run gdal_translate to convert it to a PNG: gdal_translate dataset.tif output.png -of PNG -ot byte -...
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1answer
355 views

Calculating distance between point and selected pixel in R?

I would like to obtain the distance between a point and a selection of pixel on raster image. Here the process: I read my JPEG image and extract colors I want: img.raster<-stack(***) names(img....
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0answers
179 views

Calculating pixels coordinates from lat/lon

I'm trying to develop a WPS that would print maps to images and PDFs. I don't want to use Mapfish because of its limitations, and because of some customization I need to add to the printed maps. My ...
0
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1answer
51 views

Calculating distance between each pixel of rasterstack image?

I am new on R and I have an image of class "rasterstack" of only 3 colors: Red, Green and blue as illustrated: I use this function: image = stack(img.red, img.green, img.blue) I would like to find ...
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1answer
54 views

Using GDAL Warp results in odd pixel sizes and gaps

I am mosaicking one meter and three meter rasters to two meters in Python with GDAL Warp using the following code: cl_string = "-of GTiff -co COMPRESS=LZW -tr 2 2 -tap -r near -overwrite \ -multi -wo ...
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1answer
24k views

Getting pixel value of GDAL raster under OGR point without NumPy?

I am working on a computational model of the abundance of wild pollinators across a landscape. The model itself is complete, and I am now struggling with a post-processing step. I have my GDAL ...
3
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1answer
799 views

Calculate pixel coordinates for each pixel in raster? EPSG:27700 (British National Grid)

I have some Met Office rain radar files (NIMROD binary files). These contain raster data where each pixel is a 1km grid square. I am trying to calculate the geographic position of each of these pixels ...
2
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1answer
273 views

How big is a MODIS 250m pixel in reality?

How big is a MODIS 250m pixel in reality? This appears to be a question that contains its own answer, but I have several reasons to doubt that the pixel size is actually 250m x 250m: I downloaded ...
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1answer
64 views

Creating raster with custom values? [closed]

I have a problem: I need to create a raster with all pixels values = 0, but one of these pixels must have the value = 1. This pixel has especific XY coordinates related to an in situ station. I need ...
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2answers
226 views

Calculate 16-bit elevation values from a 32-bit RGBA image?

Say a single-band 16-bit (UInt) raster with values representing elevation (meters) must be converted to a 32-bit RGBA PNG image (8-bits/band) for use in a web application. The image dimensions must be ...
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1answer
55 views

Obtain pixel coordinates of an image

I'm working with a tiff image in arcgis projected in UTM 33N and I need to obtain pixel coordinates of a specific point in the image with known metric coords (UTM 33N). How can I get them?
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0answers
56 views

Rotating orthophoto based on polygon boundary (rotated pixel)?

When I clip an orthophoto using a vector polygon, the resulting pixels orientation is north-up like as shown in the graphic below. I used Global Mapper, ERDAS, Arcmap "Clip" "Extract by Mask", "...
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1answer
183 views

Using raster stack function time in R?

I successfully ran a function over a smaller test raster stack (48 layers) in about 30 minutes but cannot run it over my large stack (1462 layers). The last one I tried over the large stack ran from ...
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1answer
40 views

Does the MODIStsp package computes the QA's and eventually corrects the bad quality pixels?

I am using R's MODIStsp package for downloading MOD11A2 time series products. While executing the command it was written that QA's were computed. Several files were created, LST_Day_1km, QC_Day, ...
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2answers
7k views

Calculate the average of neighbor pixels for raster edge

I have a small raster (or matrix) and I would like to know what is the difference between each pixel and the average of its' 8 neighbors in the case where the kernel window is on the edges and no ...
5
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2answers
2k views

How to count the number of pixels with a specific value of a .gif file in QGIS

So I have this .gif file that has values from 0-255 but not entirely grayscale. I tried the r.report and it does not work. I also tried the raster calculator like: "myraster@1"= 1 (because I want to ...
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0answers
137 views

Clean up pixel noise from raster in ArcGIS

I have this raster. It has some pixels near the main objects, this raster is a product of a classification. those little pixels have the same value of other big objects, so I cannot just reclassify. ...
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2answers
519 views

Getting all pixel values from raster image in ArcGIS Desktop?

I am using a CHIRPS raster image on ArcGIS 10.6 and there is no attribute table, I need the pixel values as it is the individual rainfall data for the stations to perform further statistics on. How ...
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1answer
93 views

Pixel count on AFR Raster in ArcGIS?

I have this kind of raster which has no pixel count in his attribute table. I'd like to calculate the pixel count by class: These are the raster's properties