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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82 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
743 views

Correct resampling method to simulate lower resolution satellite data?

I would like to simulate lower resolution satellite imagery from continuous higher resolution imagery. For example I want to use Landsat derived leaf area index data with a resolution of 30 m and ...
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934 views

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 ...
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132 views

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 ...
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1answer
164 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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449 views

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 ...
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321 views

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 ...
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579 views

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 ...
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89 views

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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17 views

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 ...
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34 views

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 ...
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41 views

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 ...
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19 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 ...
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2answers
48 views

How to calculate pixel size on image of map?

I have to save to .png file with part of map from app. I've got information about PPI, easting/northing, print resolution, map scale and map coordinate system and using this information I have to ...
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24 views

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
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33 views

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 ...
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1answer
118 views

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) ...
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288 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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86 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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221 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
142 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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447 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 ...
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277 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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64 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 ...
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0answers
167 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-...
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55 views

Saving Style as SLD in QGIS but after reloading unit changes from map units to pixel?

I have a style I am saving in QGIS (2.18) as an SLD. After reloading the Style onto the layer the ouline width changes to pixels instead of map units. I even checked the .sld in notepad and the uom-...
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0answers
783 views

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 ...
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0answers
247 views

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 ...
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0answers
272 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"), ...
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0answers
161 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 ...
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0answers
279 views

Pixel sizes, cartographic scales and maps

In spite of being a widely discussed topic, I have not been able to find the complete answer to my concerns regarding scale's use in maps preparation. I am interested in finding in the relationship(s) ...
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0answers
86 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 (...
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85 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 ...
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69 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 ...
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18 views

Adjusting pixel values of a raster based on geopandas colums or fields

I have a geodataframe with geometry column containing Polygons and 5 fields or columns('Crop1', 'Crop2', 'Crop3', 'Crop4' and 'Crop5') as well as a raster image. There are 159 rows in the geodataframe ...
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22 views

Difference in pixel size between gdalinfo and gdal2tiles

I'm getting two different pixel size values, does anyone know what is the reason for this issue? From gdalinfo: From gdal2tiles.py: GDAL version: 3.20
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14 views

Getting pixel values from lat/long values using ENVI

I am using ENVI software to process satellite image. I have two images from two different satellites and I want to get the value of the same point in the two images. I got random points from the first ...
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33 views

Measuring the intensity of raster pixels within buffers

I need to create a variable ranging between 0 and 1 to compute the intensity of a flood. I have the raster file for the flood and the layer with the coordinates of the households that have been ...
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1answer
39 views

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 - ...
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0answers
24 views

Raster - pixel values not matching legend

I am a novice at working with raster data. I extracted hundreds of .tiff files from a WMS and now I need to run zonal statistics on them using ArcGIS 10.5.1. The original map legend on the website ...
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59 views

Change a raster resolution and size according another raster in QGIS

I have downloaded two rasters set from SoilGrids (like pH, carbon stock... with 250m resolution) and WorldClim (climatic biovariables with 30s resolution). I want to use them in RStudio for Species ...
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1answer
97 views

How to extract pixel values of a polygon shape, using R for annual (365 files per year), daily NetCDF raster files?

I am trying to extract a daily value from a study area (given polygon). The files are provided as annual NetCDF files (365 of them per year) for a daily value. However, with GIS programs it would be ...
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97 views

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 ...
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37 views

How to fix SRTM half-pixel shift with GeoServer

The SRTM data has an half-pixel shift (I assume that’s what is described in the last FAQ, and that GeoServer uses pixel corner origin ? I couldn’t find this information). Despite this shift being ...
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20 views

Do all my layers need to have the same pixel type and pixel depth for an overlay analysis?

I am doing an overlay analysis with different raster layers, that were once polygons, and some original raster layers. I have resampled all my layers to have the same cell size or resolution, and now ...
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0answers
30 views

Including weighted values in zonal statistics using stand-alone PyQGIS script

I am having trouble to include the (spatial) weight of a pixel when using zonal statistics in a stand-alone python script (jupyter notebook 6.0.3 on Ubuntu 18.04.5). My data contains of a .tiff (...
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0answers
30 views

Raster Resampling / Clipping? QGIS

When I am trying to resample a raster layer or to clip it by mask layer the pixel value get automatically changed in the output file irrespective of every setting. Why it is happening and how can i ...
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0answers
20 views

Aggregate precipitation by different time intervals at PIXEL level

I am trying to create a script to calculate the precipitation registered by GPM (Global Precipitation Measurements) between TWO dates. The challenge is that these two dates are defined by the Minimum ...
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0answers
75 views

How to get the value of specific pixels in Google Earth Engine

I want to extract the value of some pixels. I have already select the pixels that I want to extract the value with this code: var pixel_snowcover = glacierfilled_M1.select('albedofill1').map(...
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1answer
163 views

How to calculate the number of pixels with a specific value in a image Google Earth Engine

I am trying to count the number of pixels who are equal and greater than 0.6 in a specific band (albedofill1). I am trying to count this for every image in my collection (glacier_final). For now, I ...