Antenna Height / Altitude correction when using Pix4d Catch & viDoc

PIX4Dcatch PIX4Dcatch Questions/Troubleshooting
1

I’m having trouble getting accurate vertical elevation measurements when using a survey pole, and I’ve come across conflicting information regarding how to correctly set the Antenna Height / Altitude Correction.

According to this (How to manage Point Collections (GCPs) - PIX4Dcatch) Pix4D support article:

“When using a Pix4D supported RTK device, the antenna height must be measured from the base of the RTK device to the ground, centered on the point.”

However, the Quick Start PDF Guide for the viDoc RTK rover & PIX4Dcatch (https://data.pix4d.com/misc/KB/Getting+Started+PDFs/EN/Quick+Start+Guide+PIX4Dcatch+viDoc+RTK+rover+EN.pdf) states:

“If you are using a pole or tripod to measure, enter the height from the point to the base of the antenna in the Antenna Height / Altitude Correction field.”

Can someone clarify which method is correct?

I’ve been measuring from the base of the pole to the base of the RTK device, but my vertical values are consistently off by about 25 cm. When I use the laser without the pole, my results are within 10 cm, which is better but still not accurate enough for my needs.

Any guidance would be greatly appreciated!

2

Update**

I found that my measurement for the pole was off by 15cm…. I must have been using a measurement to the antenna. Now my pole and laser measurements match.

I also found that my 10cm difference was that between the HTv2.0 geoid and the GSD95, which my control data was in. When using ellipsoidal height and calculating the Geoid-ellipsoid difference, I’m back to the target elevation.

3

Hello Camal,

Thank you for reaching out.

We would like to ask you to send us a support ticket for further assistance. You can do so by visiting the following link: Pix4D Technical support services .

Have a nice day!

Best wishes,