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.

Filter by
Sorted by
Tagged with
0
votes
0answers
33 views

Getting pixel size without opening raster using Python [closed]

I want to get the pixel size (resolution) of a raster without opening up the raster in gdal. I currently have my script opening the raster in GDAL using gdal.Open() and getting the resolution that way....
0
votes
0answers
23 views

Geometric Calculations for Group of Pixels

I have group of pixels that I created by region group tool and I would like to measure the length and the width of each pixel group. I need max length and the width at half of the length of each group ...
1
vote
1answer
39 views

Reclassify NDVI and count number of pixels above certain threshold in Google Earth Engine

Following on from a previous question (NDVI reclassify with mean +1SD as threshold in Google Earth Engine) I have managed to show the pixels that have value higher than NDVI mean+1SD at the estuary ...
0
votes
0answers
18 views

How to calculate the number of pixels in each class using QGIS?

I have a raster file with slope values. These slope values are divided among several classes like A,B,C. Then there's a vector map with points. For an example a point can belong to class A of slope ...
1
vote
1answer
91 views

Extract all pixels values from GeoTIFF with Python [closed]

I would like to recover the values of the pixels of a GeoTIFF of a single band. First I get the x and y coordinates and I would like to use them to access the pixel value. Here is my code: raster =...
0
votes
1answer
14 views

Pixel Size field in gdalinfo command meaning

What is the meaning of the Pixel Size field in the gdalinfo output on a TIFF image? I have 2 images, one is a PAN image (size 400MB) while one is a DEM (size 25MB). Both are in TIFF format. When I ...
2
votes
1answer
43 views

Find most contrast pixel on raster in certain range of pixels around it?

How to assign to each pixel of a raster value of the biggest difference between values of all pixels around it to a mask on 1 picture (red pixels and everything that after them is not included, black ...
1
vote
0answers
26 views

Convert lat/lng to pixel in UTM image files [closed]

This is my first post on this site so please be gentle :) I have a number of large image files that map locations around the world. These image files are in UTM projection and I am looking to write a ...
1
vote
1answer
25 views

Cannot get number of max pixels in Google Earth Engine

I have a code that calculates the max number of pixels among all the rasters it retrieves and then creates new imagecollection with only rasters that contains rasters in the size I want. For some ...
0
votes
1answer
24 views

GDAL Sentinel-1 pixel size

We know that fields related to "Geotransformation" and "projection" are empty when one tries to access these information using gdal on Sentinel-1 (at least the GRD products). I normaly use: gdal....
0
votes
1answer
25 views

Pixel resolution units

I am working with Sentinel-1 images. at this time I am focusing on S1-GRD products. Based on the Sentinel-1 dodumentation we know that GRE images are the same SLC images which have gone through ...
2
votes
0answers
49 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 ...
1
vote
1answer
38 views

Rounding to nearest multiple of pixel resolution using ArcPy

ArcPy can return the pixel resolution: arcpy.GetRasterProperties_management(rasterfile, "CELLSIZEX", "").getOutput(0)) Let's say this returns "3.2808" I wish to be able to take a given input, say "...
1
vote
1answer
36 views

Why does Earth Engine report Sentinel-2 pixel depth as 16-bit when it is 12-bit?

When accessing Sentinel-2 through Earth Engine search bar, the info page that pops up reports the bands as UINT16 when in reality they are 12-bit. Am I interpreting this incorrectly?
1
vote
1answer
46 views

Count the number of pixels according to their value using for loop

I have script that does the enxt procedures: create imagecollection from Landsat7 clip the images according to specific geometry and calculte NDVI for each one filter the rasters according to the ...
2
votes
1answer
69 views

Count number of pixels [closed]

I have two layers: polygon and raster. Could you tell me how to count the number of pixels which intersect with polygon layer? Raster is too large to creating fishnet or convert to vector (time ...
2
votes
1answer
52 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 ...
2
votes
3answers
39 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 ...
1
vote
0answers
26 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 ...
3
votes
1answer
94 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 ...
1
vote
0answers
35 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 ...
1
vote
0answers
33 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 ...
0
votes
1answer
47 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?
0
votes
0answers
15 views

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 ...
0
votes
2answers
82 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 ...
0
votes
0answers
24 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 ...
1
vote
2answers
52 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 ...
1
vote
1answer
47 views

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

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 ...
2
votes
1answer
321 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 ...
1
vote
1answer
80 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 ...
4
votes
1answer
55 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 ...
1
vote
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 ...
0
votes
1answer
140 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 ...
2
votes
1answer
132 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 ...
1
vote
2answers
72 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 ...
0
votes
0answers
40 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 ...
0
votes
1answer
72 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: ...
1
vote
1answer
64 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 = ...
1
vote
0answers
38 views

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) ...
0
votes
1answer
53 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 ...
1
vote
0answers
279 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 ...
1
vote
1answer
510 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....
0
votes
1answer
57 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 ...
1
vote
1answer
60 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 ...
1
vote
3answers
183 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 ...
2
votes
1answer
309 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 ...
0
votes
1answer
74 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 ...
1
vote
2answers
263 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 ...
0
votes
1answer
60 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?
3
votes
0answers
64 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", "...