What are good ground control points?

What are good ground control points?

Choosing good ground control points

• Choose features that you can identify accurately at the resolution of the raw image.
• Select features that are close to the ground.
• Avoid using shadows as GCPs.
• Beware of selecting common or repetitive features as GCPs such as parking lots or lines on a highway.

How do you use ground control points?

Ground control points are large marked targets on the ground, spaced strategically throughout your area of interest. If you use ground control points with your aerial map, you first need to determine the RTK GPS coordinates at the center of each.

What is the purpose of a ground control point?

Ground control points (or GCPs) are points on the ground with known coordinates. In an aerial mapping survey, GCPs are points which the surveyor can precisely pinpoint: with a handful of known coordinates, it’s possible to accurately map large areas.

How is ground control point measured?

Planar coordinates: (X/Y) coordinates, or the Longitude/Latitude in decimal degrees). Elevation: Measured relative to MSL using EGM 96 Geoid (feet/meters). Horizontal and Vertical accuracy: Margin of error (± feet/meters) as reported by the positioning device.

Do I need ground control points?

In general, there are two reasons to use GCPs: if you need a high degree of global accuracy, or if you are contracted to provide measurements within a certain range of accuracy. If your project requires a high degree of global accuracy, then you should use ground control points.

What are controlling points?

A control point is work which is aimed at checking of the compliance of the results of certain work in a business process with formulated requirements to its results. And control points by means of which the quality of business process implementation will be controlled should be organized.

Where are the best locations to place ground control points?

First, the points need to be located on the ground with clear surroundings to make sure they are visible on the raw image. A point that is on the ground beside a tall object, such as a building or tree, will have a greater chance of being obstructed in the ortho-ready image.

How are ground control points used in surveying?

Ground Control Points, or GCPs, are marked points on the ground that have a known geographic location. In aerial surveying, a drone can be used to autonomously collect photos of the survey area. If used, GCPs must be visible in these aerial photos. The photos are then processed in the cloud using drone mapping…

What are ground control points in photogrammetry?

What is ground control point in photogrammetry? Ground control points (or GCPs) are points on the ground with known coordinates. In an aerial mapping survey, GCPs are points which the surveyor can precisely pinpoint: with a handful of known coordinates, it’s possible to accurately map large areas. Why do GCPs look like that?

How to make a ground control point visible?

One important thing to remember is that the GCP must be easily visible in your aerial imagery. This is achieved by using high-contrast colors and by making sure the ground control point is large enough to be seen from your particular flight altitude.

What does Ground Control mean in Geog 892?

A ground control, which we introduced in the last section, is a target in the project area with known coordinates (X,Y,Z). Accurate, well placed ground controls are essential elements for any photogrammetric project utilizing aerial triangulation. There are two standard types of ground control points (Figure 7.9), those are: