Strayos PPK User Guide

How To Upload Your Data to Strayos platform for PPK processing

Strayos provides Post Processing Kinematic (PPK) feature to determine highly accurate locations for the drone images during the site survey.

PPK uses a GPS signal phase differentials between a base station and a drone to calculate precise location information. The same approach is used by Real Time Kinematics (RTK). The main difference between RTK and PPK is that RTK helps to collect data in realtime on the site, and PPK is post-processed over the Strayos cloud.

RTK lets you receive the data quickly but requires a consistently strong connection between the base and the drone. Losing connection momentarily can hamper data accuracy.

PPK adds extra processing time but its a simple and reliable approach. The only thing you need is the raw observation data and survey images from your drone.

Strayos web platform will automatically increase the accuracy of the photo coordinates and process your images into a 3D model.

Usually, the drone photos are geotagged, but the accuracy of geospatial data can be improved to give better results. Below screenshot shows the difference between the unprocessed and processed GPS positions of the photos. It is critical to have a high accuracy of the photo coordinates for the Strayos platform processing.

RED points indicate initial coordinates and BLUE points are processed coordinates.

There is a lack of accurate information from the drone GPS and by using PPK processing we can improve accuracy.

PPK method requires the logs from your drone and the logs from the geodesic reference base. For PPK processing we need to execute the known data and get the missing information to enhance accuracy.

Pre-requisites for PPK processing:

your images are geotagged
you have the Rinex file and Timestamp log from your drone
you have a stable network connection to upload images in Strayos cloud

Rinex.obs contains a raw log data, that contains approximate position in XYZ, a date and a time of surveying and a series of measurements from satellites constellations. This is an industry-standard for storing GNSS data.

When we open a file we can see a line approximate POSITION and a line with the date of surveying in a format YYYY MM DD.

Timestamp.mrk contains a number of the photo that was taken during the surveying, GPS data and coordinates of each photo.

However, this information isn’t enough for PPK processing. We also need to obtain the corrections from the reference base that collects the series of measurements from the GPS satellites. Currently, Strayos platform uses the Continuously Operating Reference Station (CORS) Network based in USA.

But the main restriction for this PPK approach is that the reference base station shouldn’t be placed any more than 40 kilometers from your site, because it will be difficult to provide a high-quality adjustment of the drone and base logs.

Strayos also allows users to upload their own base station RINEX files surveyed on site.

As a result of PPK processing, we can get more accurate GPS coordinates compared to non-PPK.

Let’s get into the action.

First of all, log in to your account on Strayos app. Then click the NEW PROJECT button in the upper left-hand corner of the screen to start the upload.

Step 1. Select the upload image type.