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Questions tagged [ground-control]

distinctive points or markings (on the ground), whose positions (coordinates) are known and which are visible on photos or images -- used to help correctly position the photography or imagery for mapping or GIS

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Using Ground Control Points in Agisoft Photoscan?

I'm fairly new to the Agisoft Photoscan program, but I am trying to build several models using aerial imagery and highly accurate GCPs, with coordinates collected in the field. I align my photos and ...
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Ground Control Point Experience

I have a number of aerial images that do not align with where my GPS says I am. For example, I am standing at the intersection of two roads with a Trimble R10 and a handheld IOS device with the ...
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1answer
47 views

Deleting GCP set in GEOTIFF?

How to delete GCP set in GEOTIFF? I have some GEOTIFF files. They have been set for GCP, but I made a mistake. Therefore, I want to take the following procedure. Delete the set GCP. Grant new GCP. ...
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32 views

GDAL: Using gdallocationinfo on a rotated SAR image to get pixel value at Coordinates

Some information: I must not re-sample the image, the pixels are rotated, and the image opens in Arcmap just fine. now, there are 15 GCPs on the raster (which make the pixels rotate) Progress: 1.When ...
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1answer
31 views

ArcGIS 10.5 - Testing the accuracy of a satellite image's georeferencing using dGPS ground control points

I want to test the accuracy of the georeferencing of a satellite image by using a set of independent ground control points collected in the field via differential GPS. Is there a tool/method/...
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1answer
191 views

How to create a GCP (*.points) file from a Shapefile (points layer)

I have created a points layer which represent Ground Control Points (GCP) for georeferencing scanned topographic maps via 'Add Layer > Add Delimited Text Layer', where I saved coordinates in a .csv ...
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Orthorectification on a DSM

I would like to orthorectify on the features (trees and buildings), noted that with may cause some stretching or tearing on the image due to the obliquity of the look angle. I'm only interested in top ...
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1answer
28 views

Georeferencing CAD drawing and setting ground control points in GRASS?

I'm fairly new to QGIS and Grass GIS, and learning the interface. I have a CAD drawing that has no coordinate system assigned and needs to be georeferenced to NAD83 HARN Northern Colorado (feet). I'...
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68 views

Error importing ground control points ArcGIS Pro

I am working on processing aerial images from an automated drone flight in ArcGIS Pro. The photos import into the Ortho Mapping workspace just fine, and the Quick Adjust alignment runs without ...
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1answer
37 views

What does control points look like in viewer ? How spread do they need to be ?

I have a question for you . As I am working on using ERDAS Autosync to orthorectify from an ungeoreferenced aerial photos to known reference image. I have a DEM that to go with it as well. I ...
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1answer
168 views

Georeferencing X Y (AND Z) with GCPs in QGIS

I have GCPs recorded to centimeter precision in lat, long, and elevation. I want to georeference my UAV-photogrammetry-generated GeoTIFF and DEM with these GCPs (since the GPS on my UAV is only ...
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1answer
396 views

Editing/adding GCPs using QGIS?

I have georeferenced some aerial images, loaded in QGIS and saved them (files .tiff, aux.xml and .points). These images overlap, however I found that some details in the borders did not match exactly ...
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How are ground control points collected that aren't in WGS84?

I understand that if you collect GCPs using an RTK GPS they are in WGS84 / EPSG:4326 - and you could then convert them to another EPSG. But I'm wondering how GCPs are collected in other coordinate ...
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Are all remote sensing landcover/use classifications without ground survey scientifically invalid? [closed]

It is on the need of accuracy assessment of classification product. Land cover/use classification is a prominent analysis in remote sensing. Now the question is if I generate a landcover from LANDSAT,...
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1answer
121 views

How to apply control points in LiDAR?

I am new to LiDAR point clouds and I have a big issue. I have LiDAR data for 30 km and I have 5 - 6 control points. My point cloud is inaccurate (have averagely 3-4 m error in xy and 50 m error on ...
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1answer
51 views

Change project CRS = discard GCPs?

[Using QGIS 2.12 Lyon on Mac with OS X 10.10.5] I am struggling to georeference some old hydrographic survey maps that are in the form of TIFF files (.tif). If I open the georeferencer tool and set ...
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1answer
59 views

Can targets placed on the facades of a building be used to increase the accuracy of a point cloud of a building generated from Drone/UAV/UAS imagery?

Can targets (used for registering point clouds) mounted on a building be used to increase the accuracy of a point cloud generated from UAV imagery?
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1answer
818 views

Why do collinear ground control points create larger residuals?

When georeferencing a raster image of a long corridor, why do collinear ground control points cause larger residuals? Say I am using the georeference function in ArcMap, and I have 6 ground control ...
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161 views

Finding angle to north on image with three control points

So I am working on some software that geolocates spots on a map taken from a drone. I am having some trouble with the actual geolocation when the map that the program is given is not aligned north. ...
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1answer
242 views

UAVs and using ground control

I have been having a conversation at the office about whether to use ground control when using drones/UAVs to capture aerial images. The ground control that I am referring too is any permanent survey ...
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1answer
85 views

Satellite image vertically squeezed after being georeferenced

I am using ArcGIS for Desktop 10.1. I am trying to georeference a Google Earth image in Christchurch area, New Zealand. I am using some CGPs I have got from this image (their Google Earth coordinates),...
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1answer
980 views

How to do geometric correction of remote sensing data in R?

My challenge is to replace most of the remote sensing commercial tools with R code (I'm teaching assistant at the University and I would like to move to open source R code to show the added values to ...
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489 views

AGI STK Server alternative

AGI has a server product called STK Server that exposes REST services to perform satellite acquisition planning. However the cost is astronomical $200k+ (pun inteded). They also have STK components (...
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3answers
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Using PROJ.4 library to transform from local coordinate system coordinates to global coordinate system using ground control points?

I have a point cloud whose coordinates are with respect to a local coordinate system. I also have ground control points with GPS values. Can I convert these local coordinates to a global coordinate ...