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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What do the numbers on the scale mean when I zoom in and out
I am using a map that overlays carbon emissions over geographies produced by a satellite. When I zoom in and out, the number on the "scale" changes. I want to know what this number actually ...
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QGIS: Export ShapeFile-Layer with image coordinates
I am completely new to QGIS and I am trying to solve this issue:
I have 3 layers: OpenStreetMap, an image and my shapefile layer with polygons.
All polygons are within the image.
Is it somehow ...
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Extract values of surrounding pixels in a raster from QGIS
I can extract values from raster by "raster to points" tool but I need to find values of surrounding eight pixels to the central pixel. And I need to do this for all pixels so I could put in ...
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Query: Raster alignment in QGIS (pixels without data)
I would like to know if when aligning rasters of different resolutions in QGIS if it is possible that some areas that do not have data can somehow be modified or interpreted to give an explanation ...
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All the pixels in an image exported from Earth Engine have the same value
I'm trying to export an image with 42 bands from Google Earth Engine:
Some bands correspond to an index like NDBI for Sentinel 2 images and his equivalent for Sentinel 1 images, other band correspond ...
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Creating raster based on function of distance to points and assorted attributes in QGIS
In QGIS 3.30 I have a dataset of points associated with several values, call them integers A and B.
I want to create a raster with maybe 5km x 5km pixels where the value associated with each pixel ...
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Removing pixels within given threshold in ArcGIS Pto
I have a time series of Landsat Tiles where I have attempted to mask out the clouds on each image and calculated NDVI but still get some outlier pixels.
Is there a way for me to remove outlier pixels ...
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Looking for QGIS equivalent of ArcGIS "Group values" tool
I have LULC 8 classes. I want to group them in QGIS into five priority score classes in Symbology, just the same as the function in ArcGIS "Group values". But I can't find the same tool in ...
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Exporting MERRA2 image with Google Earth Engine with same resolution
I am trying to extract MERRA2 columnar dust data from Google Earth Engine for a specific range of dates. I have to download it as daily data so I have converted it from hourly to daily. The image's ...
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Counting the total observation per pixel
I generated a water mask using MNDWI. Now I would like to count the number of total observation and water detection per pixel as Global Surface Water dataset from JRC. I successfully counted the ...
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How to delete Individual Pixels from Raster image in ArcGIS Pro?
I need to remove some pixels that are not in homogeneous land-covered areas.
How can I do that?
I was told to convert the raster into polygons, but that didn't work, as some pixels were merged ...
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Cloud pixel filters for Sentinel-2 images
I'm trying to perform a supervised land use classification for a region (Buenos Aires Delta) and a specific time period (between January and March 2017). I'm using Sentinel-2 images processed in GEE ...
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Get pixel values using rasterio.sample
I would like to get the pixel values for a single point within a .tif file using rasterio. I have read several previous questions, and implemented the suggestions.
Here is the code that I am using:
...
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NDSI handling of areas that cross over a pixel
I am using GEE to calculate the NDSI on Landsat8 using a polygon area of 500m.
Since Landsat8 has a 30m pixel resolution, I wondered how the partial pixels are handled in the calculations.
Are they ...
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Create raster with angles between single point and all raster pixels in QGIS [duplicate]
I would like to create a raster in which the cell values contain the angle between that cell and a single vector point. It would be as though a line were projected between the cell and the point, and ...
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Merge raster data whilst keeping min value and their layer name [closed]
Using numpy and arcpy I can’t figure out a method to do the following:
Merge two rasters which have identical cell alignment keeping the minimum value (e.g compare the pixel values and keep minimum)
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How can I get the longitude and latitude of a specified pixel (e.g. equal to certain value) with Google Earth Engine?
I want to get the longitude and latitude of a specified pixel (e.g. equal to a certain value) using Google Earth Engine. In other words, I have used "ee.Reducer.min()" to get the minimum ...
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MapServer - Adjust brightness and contrast of a layer
I'm completely new to GIS/MapServer stuff. I'm working on an application that displays geotiff images on a 3d earth/map. I'd like to be able to adjust the brightness and contrast for this imagery via ...
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Pixel-wise regression between the independent variables tmax, tmin, prec and the depending variable srad after they are clipped in R [duplicate]
I have WorldClim version 2.1 climate data for 1970-2000. This version was released in January 2020.
There are monthly climate data for minimum, mean, and maximum temperature, precipitation, solar ...
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Pixels not matching with GDAL projection of Modis LST hdf data [duplicate]
I have used the following the commands to project MODIS LST .hdf data through GDAL in cygwin:
gdalwarp -r bilinear -of GTIFF -tps -t_srs '+proj=utm +zone=29 +datum=WGS84' HDF4_EOS:EOS_SWATH:"...
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Backward transformation of georeferenced image: from GeoTIFF to TIFF
What's the processing procedure to realize a backward transformation, from a GeoTIFF image to its native array of pixels?
Do you have any suggestion?
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Calculate area NDSI in GEE
I am new to using GEE.
I am trying to calculate the area of NDSI values gte 0.
For this, I make a function where I already do the conditional.
So I have images with values 0 and 1. Then I added a band ...
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Better workflow for extracting boundary of raster in QGIS
I have got a raster (.tif) which has areas with "no data". I want to extract just the area where i have data.
I can do this with gdal:polygonize (1) and native:dissolve (2).
But especially ...
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Grouping single-band GeoTIFF with 50 unique values into three categories using QGIS
I have a few (very large) GeoTIFFs from a scientific agency that use a single band to categorize each pixel of satellite imagery into one of about 50 categories ("Native forest," "...
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Rectangular cells versus square cells, is there some advantage?
I would say 100% of my work involving rasters is with rasters where the cell shape is square, e.g. 30m by 30m.
I recently received some NetCDF climate data and when I used ArcMap to visualise the ...
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Google Earth Engine - Pure pixels within farm boundaries
I would like to clip a MODIS image (coarse pixel) with a farm´s limits, but only for the pixels that are fully inside the limits. Looks like when using the "clip" function, it includes a ...
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Exporting high-resolution MODIS image from Google Earth Engine
I'm trying to extract from Google Earth Engine a large raster based on MODIS 250m data. However, when it gets sent to Google Drive, the resulting .tif has only a few pixels.
Here's my code for ...
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Export too large issue in Google Earth Engine
Here is the path to my script- https://code.earthengine.google.co.in/?accept_repo=users%2Fujavalgandhi%2FEnd-to-End-GEE&scriptPath=users%2FchakrabortySoumik95%2Ffirstprogram%3Asentinel%20Australia%...
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How do I extend a raster layer distance while maintaining the exact cell size and position of the original layer within it?
I have a raster layer that is currently 83x84 pixels wide, but the pixels have a pretty weird and specific size: 0.002083333301204805168,-0.002083333297619031996. I'd like to expand this layer a lot ...
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Creating mosaic with filenames for each pixel in ArcGIS Pro
I am producing mosaics from multiple processed landsat scenes. The final product contains maximum values from several rasters. I would like to connect the value in each pixel of the mosaic to the ...
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R lidR buffer pixels in pixel_metrics?
Is it possible to buffer individual pixels when computing metrics with pixel_metrics?
For example, if we create a 20m raster, I want to compute metrics for 30m radius squares and store them in the 20m ...
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Identifying and replacing specific pixel in DEM using ArcGIS Pro
I have a DEM that has a handful out outliers, but I have no idea where they are within the DEM. I'm using ArcGIS Pro and I have used the outlier tool to try to identify the offending pixels, but there ...
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Basemaps are blurry/pixelated in ArcGIS Pro
I recently migrated from ArcMap to ArcGIS Pro and I am having trouble with the clarity of the basemap (whether World_Hillshade or World_Shaded_relief): It appears pixelated/blurry.
I have imported the ...
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118
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Get list of longitude and latitude for non-null pixels in a region (Earth Engine)
I'm trying to extract the pixel's mid point longitude and latitude value in GEE firms dataset where a fire has occurred. I filtered the image collection ee.ImageCollection('FIRMS').filterDate('2020-...
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Reading and storing 1st pixels from multiple rasters
I want the code to read 1st pixel from a bunch of rasters (for eg. 1st pixel from 6 different rasters (having same extent and same number of pixels) and convert it into array followed by reading 2nd ...
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Calculate value per unit area from raster in QGIS
I have a raster (GeoTIFF) of number of people per pixel. I would like to convert this to a new raster of population per unit area. In other words, I would like to divide each value in my existing ...
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transform latitude and longtitude to pixel coordinate
I am trying to draw latitude and longtitude unit polygon on an image. Firstly I converted latitude and longtitude to pixel coordinate by these codes:
#Coordinates of the image that was taken by ...
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Find raster pixel coordinates on shapefile polygon corners using Python
I have a raster file and shapefile with multiple polygons.
How do I find raster pixel coordinates on shapefile polygon corners?
Not the geographical coordinates based on CRS, but the pixel row and ...
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Creating/generating centroids point features from raster image in console in QGIS [duplicate]
I have a 1-band TIFF/raster file showing a value for each raster cell. I want to get those cell/pixel values of the TIFF extracted to a CSV file.
I guess there are two ways of doing this.
First, ...
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How to stack layers (slope, curvature, aspect, etc) derived from DEM to form multi-band images in QGIS?
Made a DEM from Landsat imagery and derived the aspect, slope, curvature, TWI, etc layers (generic flood conditioning factors). I now need to incorporate these layers and feed them to a LSTM neural ...
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Pixel-based regression using xarray has incorrect P-value, but everything else is correct
I am using the code from this website to perform a regression on each pixel of an image time-series of rain and NDVI. The code works for everything, that is the outputs match the outputs of scipy, for ...
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How can I change the pixel-size from degrees to meters? [duplicate]
I have a Martian DEM whose pixel size is specified in degrees instead of meters. I was trying to convert in Global Mapper but it didn't work. Now I am trying convert in QGIS with projections but it ...
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Getting pixel values from MODIS level 3 product using ArcMap
I wanted to find and map pixels with a certain chl value from the downloaded MODIS Chl data from NASA ocean color web. When using 'identify' tool (ArcMap), I can view the particular pixel value but I ...
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Pixel size convert from degrees to meters of Martian DEM
I have a Martian DEM whose pixel size is specified in degrees instead of meters. I was trying to convert in Global Mapper but it didn't work. Now I am trying convert in QGIS with projections but it ...
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How do I generate a grid where each cell is equal to 500 px at 1:250k scale?
I worked this out once but I forgot how I did it. Somehow the grid size created a whole number of cells.
I have a map with the following extents:
xmin = -20037508.3427892439067364
xmax = 20037508....
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How to compute partial correlation of pixels in R
For example, I have 20 years'NDVI and temperature and precipitation rasters.
At first,I computed the pearson correlation coefficent with those codes as belows.
library(terra)
library(Hmisc)
ndvi <- ...
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Rasterize a vector layer where pixels just need to include a vector inside, not necessarily on the center
QGIS(3.22) I'm trying to compare a vector layer to a raster layer by rasterizing the layer to the same pixel size as the raster and then using raster calculator. I just want to know which pixels in ...
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Finding maximum value on raster transect between two points using PyQGIS
I have a raster layer and two points with their coordinates, and I want to find the maximum raster value on the line between these two points.
Is there a built-in function in PyQGIS to find the pixel ...
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Extract selected pixel values with their coordinates
My goal is to get the coordinates of all pixels with a specified value (ex: maximum and minimum pixel values).
# imports
import numpy as np
import pandas as pd
import geopandas as gpd
import rasterio
...
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Using extract by mask in ArcGIS Pro about rows and columns
I want to clip a precipitation raster to fit my study area. I have a standard raster of my study area whose rows and columns are 1510 and 1656.
However, when I use "extract by mask" tool, ...
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