# Quality Report - Difference between. "Absolute Camera Position and Orientation Uncertainties vs Relative Camera Position and Orientation Uncertainties""

Hello there,

Could you kindly please provide more deeper explanation about “Absolute Camera Position and Orientation Uncertainties” and “Relative Camera Position and Orientation Uncertainties”?

What does it really mean by "Absolute " and “Relative”?
What are the differences between these two?

Hi Sang-Yeop,

Welcome to our Community! This is a very good question!

The Absolute Camera Position and Orientation Uncertainties refers to how confident PIX4Dmapper computes the position and orientation of each image. PIX4Dmapper takes into consideration of many sources of information to compute the position and orientation with the least amount of error possible. These variables include manual tie points (MTPs), automatic tie points (ATPs), initial image position (geotags), and ground control points (GCPs).

For example, if these sources agree with each other, PIX4Dmapper will have a greater amount of confidence in computing the position and orientation of each image. If these sources don’t agree with other and have conflicts, there will be greater uncertainty in the computed result.

In terms of the Relative Camera Position and Orientation Uncertainties, keep in mind that relative camera position is related to the movement of the camera’s position to the target object and other cameras. Therefore, this needs to be optimized for a more accurate/ correct reconstruction to be built. The Relative Uncertainties here are computed only based on the ATPs and MTPs (no GCPs, no image geolocation). The relative uncertainties give an indication of the uncertainties of the relative calibration and computation of the camera positions.

In general , absolute (position/accuracy/uncertainties) discusses the relation to its true position on the planet. The relative (position/accuracy/uncertainties) discusses the relation in reference to certain landmarks, features, known locations. When it comes to reconstruction, it means the relation to features within a reconstruction. For example: if a model of a building shows windows two meters apart, and this is the same distance as on the actual building, the model has high relative accuracy.

I am sharing these resources in case you haven’t had a chance to visit them.
If you have visited all of them, please don’t mind me.
Community: High absolute camera position and orientation uncertainties Z component
What is absolute accuracy and relative accuracy?
Absolute Camera Position and Orientation Uncertainties
Relative position and orientation uncertainties
Quality report specifications

I hope this info helps. Looking forward to seeing you in the community more!

Warm regards,
Rosana Lin