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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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How to get pixel coordinates in QGIS georeferenced output map?

using the QGIS Georeferencer GDAL plugin, I can select GCPs (ground control points) on a map (plain raster input map image in a format like PNG or TIF) in an unknown projection and boundaries, and ...
jmarina's user avatar
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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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Transform pixel-coordinates from input image to pixel coordinates in output image

How can I transform pixel-coordinates from input image to pixel coordinates in georeferenced output image? I want to georeference images (frames of a video) with GDAL and GCPs. But besides the ...
urancle's user avatar
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Scatter matrix using pandas does not reset any graph

I would like to find the statistical correlation between all the pixels of an image in relation to the bands. In my case 7. from osgeo import gdal from osgeo import gdal_array import numpy as np ...
vins_26's user avatar
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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 ...
Tua's user avatar
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Mapping pixel coordinates to lat lon

For a deep learning project, I trained a YOLO based model to detect objects on satellite images (from spacenet dataset; epsg:4326). However, as the Darknet only takes JPG/PNG images as input(to the ...
SirPunch's user avatar
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Extract pixel values at given point dataset and if masked find the nearest pixel value

I need to extract the values at each pixel foe a feature collection from an image and if they are masked the value at nearest pixel, my feature collection is named table and the image collection I am ...
somya's user avatar
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Prevent pixel doubling for a mobile display - OpenLayers

I'm programming an OpenLayers (4.6.5) map with a layerswitcher in order to switch between my different layers. On mobile, the display of my layer is blurry, OpenLayers is doubling pixels and I don't ...
Adrien's user avatar
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NDVI raster to polygon in QGIS

I have an NDVI raster created through a Parrot sequoia and Pix4D. When imported into QGIS 3.0.2 it is shown as a singleband gray render type with a range of -0.355826 to 0.905562. I want to create ...
Christina Robinson's user avatar
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QGIS change pixel size after multiplication in raster calculator

QGIS change raster size after multiplication in raster calculator: I have layer with size 25x25 pixel as you can see in the picture: When I multiple this layer * 0 in raster calculator (I need clean ...
Davidm176's user avatar
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Choosing pixel size when projecting raster from geographic to projected coordinate system

I have a raster showing animal abundance (straight count) in all of Canada. The raster was created unprojected in GRS 80 with a pixel size of 0.0833 decimal degrees. I was ask to project this raster ...
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What are the shades (vertical lines) in the orthomosaics?

I am an expert on my field. I work with remote sensing. Mostly UAVs. I collect datasets and extract features from it. This year, I started collected with the Astro Freefly and the Sony A7RIV sensor (...
Jose Luis Landivar S's user avatar
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27 views

Improve image quality of "Decoration"

I imported a key using Decorations -> Image in QGIS 3.32 and the quality is poor, especially if the image is made smaller. I do not mean that the actual image file is small, but that displaying the ...
Nadka's user avatar
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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 ...
Ivan Insua's user avatar
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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 ...
Wtow's user avatar
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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 ...
Vakos's user avatar
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Is the position coordinate of a pixel the center coordinate of that pixel?

Is the position coordinate of a pixel the center coordinate of that pixel? For example, in an image composed of 4 pixels as shown in the figure below, the coordinate values of 150 and 150 are put in ...
bsg's user avatar
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How to calculate the accuracy of georeferenced aerial images in meters if the mean error is in pixels?

I have scanned aerial images taken shortly after WWII and have to georeference them and calculate the mean error. I use the Projective transformation so the error after transformation is shown in ...
Pepe Pesh's user avatar
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Extracting value of each pixel of a tiff file

I have a aggregated tif file, and I want to extract the value of each pixel in the tif file. Here is my code to read values of each pixel, but all the values I got were nan. I do not know why. import ...
Hanxi's user avatar
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RGEE getting pixel values and latitude and longitude

I am using Google Earth Engine on R. I'm trying to get a data set with the latitude and longitude of each pixel along with the value from the GEE Image Collection. I know its been done in JavaScript - ...
jen.ali's user avatar
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Acquiring pixel data from TIFF-file into CSV-file in QGIS

I have a TIFF-file which gives me a value of forest age per pixel in the whole Amazon basin. I am trying to do a spatial-statistical analysis between forest age and climatic variables. For this my ...
Andrea Rey's user avatar
1 vote
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163 views

ArcGIS Pro 2.5.0 - Is there any way to snap a polygon / feature class to pixels within a Raster?

I need to clip a raster to a specific area of interest, and a specific number of pixels. Whilst I can manually draw my AOI feature class and get the right number of pixels, it generally contains a ...
JA_GIS's user avatar
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Vectorizing a raster zone map without the lines turning into squares QGIS

Raster zone lines turn into squares after vectorizing my raster because of pixels between color zones QGIS
jack's user avatar
  • 29
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Focal regression 3x3 group of cells

I have two raster with same resolution and dimension: water-occurrence index and rainfall (mm). I want to create a new raster of SLOPE (a) and INTERCEPT (b) by performing linear regression between ...
user97103's user avatar
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1 answer
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Convert lat/lng to x/y pixel 2D PNG image

I have a 2D PNG map which I know the corners of my image and I also have the image size all as below: image size: 600x600 pixel top-right coordinate: (35.74706129,52.08012633) => (lat,long) ...
amir hodaee's user avatar
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173 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 ...
mazinga's user avatar
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482 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 ...
hopieman's user avatar
  • 111
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1 answer
376 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 = ...
matte85's user avatar
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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 ...
Faz B's user avatar
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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. ...
Alvaro Morales's user avatar
1 vote
0 answers
133 views

How to get the area of the pixels of a raster in Africa Lambert Conformal Conic CRS in R

My question has been previously asked here (R How to multiply the values of the raster pixels with the true surfaces of these pixels?), I have to multiply the precipitation value of each cell by the ...
Basilique's user avatar
1 vote
0 answers
493 views

Color different of two Sentinel 2A (L1C) images from the same sensing date

i'm new to this GIS Q&A websites and remote sensing as well, so sorry for this too basic question. It's about my Sentinel 2 (Level-1C) images. I downloaded 2 images with the same sensing date (09-...
birdseye77's user avatar
1 vote
0 answers
374 views

Pixel values change after clipping a raster layer

I'm trying to evaluate mean temperatures for the distribution area of European fish species. Therefore, I downloaded the E-OBS data set for mean annual temperature in Europe (0.25 deg. reg., "TG"), ...
Ruben's user avatar
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1 vote
0 answers
205 views

Tool in ArcMap for capturing ROIs of same size?

I'm trying to run supervised classifications and need all ROIs to be the same size. I'd like to capture the ROIs in ArcMap and so far can only find a tool which allows you to draw your ROIs by ...
RoeG's user avatar
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1 vote
0 answers
92 views

Where does the snapshot command take its pixel samples from?

I'm using the snapshot command in QGIS with a horizontal extent from 0 units to 24 units to create an image with a horizontal resolution of 4 pixels. Are the output pixels located at 3,9,15,21 (...
And G's user avatar
  • 121
1 vote
0 answers
92 views

How to integrate set of neighboring pixels in raster dataset?

I generated peaks of tree crowns as an individual pixels from DSM dataset, but there are some trees that have more than 1 peaks. I would like to integrate them based on the threshold value, for ...
Sher's user avatar
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1 vote
0 answers
87 views

Mosaic DEM has large pixel when displayed in ArcMap?

I created a mosaic dataset in ArcMap 10.2 from tiles of ASTER DEM's at 30m resolution. I am attaching the image of what my export looks like. You can see that there are extremely large, alternating ...
WendyC's user avatar
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1 vote
1 answer
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Image Segmentation tiff files for Object Detection

I have tiff files generated fro 12 bands of sentinel-2a data. I want to label each pixel of the tiff files as belonging to copper mine or normal. After labelling I want the image format to stay as it ...
user2777's user avatar
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0 answers
36 views

Converting latLng to screen point

I have a map in RN app on iOS and I have and overlay outside of the map Inside overlay I need to draw a View with some absolute position that will match some LatLng coords on the map I know screen ...
Sedoyjan's user avatar
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0 answers
30 views

Extracting forest patches using square Kernels around shapefile point data in Google Earth Engine

I have an image representing global forest cover named minArea. Pixels are valued 1 or 0 (tree cover or no tree cover). I also have a shapefile imported through my assets of XY coordinate data. ...
MrBeardo's user avatar
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0 answers
48 views

Pixel by pixel comparison in Google Earth Engine

I have attempted to write a surface water detection program in GEE using the NDWI, with otsu thresholding and canny edge filtering. I would like to evaluate my approach and I was thinking of using the ...
mdansfo's user avatar
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0 answers
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How to save the error: Array: No numbers in 'values', must provide a type

I'm a beginner of coding and GEE. I'm trying to extract the NIR and Red band time series data of each pixel in the survey area with cloud masked. However, when applying the code below I used to do ...
TIANRUN XUE's user avatar
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1 answer
36 views

Adding pixel-level classification to ee.ImageCollection

I am working with ee.ImageCollection('LANDSAT/LE09/C02/T1_L2') data pulled from earthengine-api in Python. I have previously defined a function to mask cloud, shadow, water, and snow. based on the ...
richard.turner's user avatar
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0 answers
49 views

No numbers in 'values', must provide a type

I'm facing an error when trying to export all the pixel value of a ImageCollection. The error is : But when I check the corresponding image in my dataset I don't see anything different from the other....
Aurélien Lengrand's user avatar
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0 answers
49 views

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 ...
EmZ's user avatar
  • 101
0 votes
0 answers
53 views

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 ...
Life4Gaming's user avatar
0 votes
1 answer
92 views

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 ...
Zaara Kidwai's user avatar
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0 answers
40 views

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 ...
Diego_12's user avatar
0 votes
0 answers
96 views

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 ...
Roger Godofredo Rivero Morales's user avatar
0 votes
0 answers
142 views

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 ...
Fernando Fuentes Martins's user avatar