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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37 views

Set all raster values from decimals to integers on OQGIS

I have a raster map made up of numerous pixels with decimal values. Is it possible to change these values from decimals to integers?
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1answer
120 views

Setting pixel value from 0 to 10

How can I change the pixel value from 0 to 10 on QGIS?
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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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15 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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20 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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13 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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31 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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3answers
89 views

Decreasing resolution of binary raster layer, but retain specific data using QGIS

In QGIS 3.16.2, I have a binary raster layer in which I would like to decrease map resolution without losing any value = 1 pixels (white in the example). I have tried exporting and changing the pixel ...
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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
43 views

Memory limit eror counting every pixel in an image with Google Earth Engine

I am trying to count the number of pixels in my large AOI (roughly the size of the state of Iowa) for a Landsat derived image. To get a rough pixel count, I could divide the area of my ROI by 900 (...
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1answer
37 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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1answer
39 views

Pixel Editor disabled in ArcGIS Pro

I'm using ArcGIS Pro 2.4.0 with Windows 10 to edit a few pixels in a raster. I'm creating a map of areas connected to the ocean and there are a few corners of narrow inlets that I need to correct to ...
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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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58 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
84 views

Editingt pixels of raster (geotiff) file using QGIS

I have a raster file which I want to edit. My raster is the output of a classification (on Google Earth Engine), but some pixels in the edges of some features are wrongly classified (inside the red ...
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1answer
44 views

Calculating wealth values from richness in QGIS

I have 6 species distribution maps. These species are modelled under certain climatic conditions. As a result, I have 6 raster maps. I would like to obtain a map that shows the richness of these 6 ...
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0answers
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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2answers
53 views

Counting pixel values of NDVI

I'm trying to calculate the amount of pixels with the value of 0.3 to 0.7 between two different rasters (each raster of a different year) to calculate the loss of green spaces trough time. Is it ...
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0answers
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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1answer
96 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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0answers
91 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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1answer
55 views

Extracting time series of one pixel from the SMAP soil moisture (soil moisture in %) product

Currently I am writing on my script to extract a time series of SMAP pixel values of the band 'smp', however, my studyarea is rather small and hence the script I found online in this community from ...
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36 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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2answers
47 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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1answer
149 views

Count pixels inside a polygon with Google Earth Engine

i'm pretty new on GEE, so i hope someone can help me with this. As the title say, i'm looking for a way to calculate how many pixels i have inside a polygon. I tried to do it with reduceRegion and ee....
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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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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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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
31 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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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
19 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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1answer
68 views

PDF export from QGIS print layout: line fill pattern vectors shown with pixelation

I have created grayscale piecharts in QGIS 3.14 Pi on Win10 with geometry generator. So the piecharts are vectors, created with the expression editor, using the wedge_buffer expression. I created a ...
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72 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
155 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 ...
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1answer
93 views

How to reduce pixels in polygons by calculating mean in Google Earth Engine?

I'm new at Google Earth Engine environment. I would like to create a time series chart with many large polygons but I get this error: Error generating chart: Error in map(ID=...
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1answer
12 views

How to decrease the size of a pixel in a collection of images?

How to decrease the size of a pixel in a collection of images? I need to take the PERSIANN images and reduce the pixel to the size of the CHIRPS. One has 0.05 ° resolution and the other 0.25 °
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1answer
111 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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23 views

r.walk issues in GRASS

I have been doing the r.walk analysis but fail to generate the result. The movement direction map and walking cost map from stop points is extremely small, limited to a 3x3 or 5x5 square. Does anyone ...
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0answers
79 views

How to apply a cloud mask on a MODIS collection in Earth Engine

I am trying to work with the MODIS dataset from google earth engine (MCD43A4.006 MODIS Nadir BRDF-Adjusted Reflectance Daily 500m) and I want to apply a cloud mask but I have no clue how to do it. I ...
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0answers
42 views

Google Earth Engine: When mean pixel value is blank, take nearest pixel value

I have a code for calculating the mean value of a variable, and reducing it to get values for 5 regions of interest. The full earth engine code for this is here. However, I'm getting blank/null values ...
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0answers
13 views

Orientation in 3D coordinate space of a pixel in georeferenced video imagery

I am trying to find (a) method(s) to extract the position in 3D coordinate space of a bounding box (detected object in 2D video imagery) having knowledge the below: I have multiple images with ...
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1answer
345 views

Getting table with coordinates and pixel value for polygon from Google Earth Engine

I would like to have a table or a matrix with the coordinates and value of each pixel on a given polygon. I am working with the Global Forest Change data specifically with the 'loss' layer. In this ...
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1answer
310 views

Counting number of unmasked pixels per image in collection using Google Earth Engine

I'm trying to count the number of pixels that are masked by the cloud mask of the image collection given by the Earth Engine dataset. I have clipped my collection with a ROI and now I want to keep the ...
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0answers
27 views

Changing pixel values in ArcMap

I have a tif file that needs some pixel values adjusted in ArcMap. I have a pixel with a value of 44 that I need to change to 58. In the Raster Calculator I'm using Con("tif" == 44,58,"tif") but that ...
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0answers
78 views

Get pixel snapping using for variable feature extents (using GDAL/rasterio)

I would like to apply consistent pixel snapping/origin to multiple rasters of same CRS and resolution (pixel size), but different extents using GDAL and/or rasterio. In terms of functionality, I am ...
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1answer
25 views

Why it doesn't mask the complete layer?

Through the code I need to calculate the number of pixels of a layer composed by three classes (severe, medium and low), but the code just take into account the medium and low classes. https://code....
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1answer
35 views

How not to lose columns in a result of a pixel extraction, if some column is equal to zero?

I have reclassified some classes of a raster into two classes (natural and anthropic) and I have to extract the pixel proportion of each class for some study areas that I have. However, there is a ...
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1answer
210 views

Count connected pixels (GEE)

I am working on a code to detect/count the patches of burned areas in an image. I thought using the function connectedPixelCount() in GEE would help me in doing so. However, the latter seems to not ...
2
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1answer
44 views

Extracting pixel values by overlaying polygons

I am trying to extract pixel values by overlaying polygons. I use a code after Patrick Grey (http://patrickgray.me/open-geo-tutorial/chapter_5_classification.html). When I masked the image with the ...
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1answer
84 views

How to translate a pixelCoordinate between different map sizes? OpenLayers 6.3.1

My starting point for this question is the ability to print a map with a given format&resolution, very similar to the "Export to PDF" example at OpenLayers webpages: https://openlayers.org/en/...