If you are like me and of a certain age you will have come from an era where GNSS system were cumbersome and extremely expensive. At best back in the late 90’s and early 00's an expensive €30k kit was primarily used for getting spot levels in open areas. Any thought of getting near a hedge or under trees was no more than a pipe dream in those days.
Roll on 25 years and our GNNS systems are the most important tool in our survey toolbox. With the addition of new GPS constellations such as Galileo & Beidou it has become very rare to see fewer than 20 satellites on screen. I remember back in the day working with maximum 6 satellites and that was only for maybe 3 hours in any given working day. We had to tailor or days work around the best few hours in any given day.
Coupled with the technological advances made in recent years we now have a mindset when we go out to do a topographical survey that we should get this entire survey completed with GNNS receivers. It has become commonplace now in our business that a total station is only needed for small areas of infill or key details such as ridge and eave heights on buildings.
Just when we thought we could not take this technology any further along comes the TILT function. Using IMU Tilt has taken GNSS surveying to a whole new level. So what is TILT? Put simply it is the ability to record detail, such as walls, buildings and other detail, which would normally be the unique domain of a total station, without having to be vertically over that point. It allows the user to TILT the GNNS receiver up to 50 degrees out from the point of interest and the brains of the kit accounts for the tilt to correctly place the point in its correct location.
At first we were very sceptical. It is just built into us surveyors that a pole needs to be vertical right? Well not anymore. We took the plunge one day and decided to test the function while recording the same detail with a total station. We were blown away how accurate the TILT function was. 10mm was the worst error and for a topographical survey that is well within tolerance. After exhaustive testing we proved to ourselves that TILT was the way to go.
A year in and we have increased productivity by 30% on every single survey and that is not an exaggeration.
The biggest moral survey test of all was to set out using TILT. Again, with trepidation we tested and tested and could not believe the results we were getting. You think increased efficiency while recording points for a topo survey is good. Just wait until you see how fast you move with TILT in a setting out environment.
Of course there are things you really need to keep an eye on when using TILT. As the algorithm calculates versus the height of your pole you have to make sure that you 100% have the correct rod height input, otherwise you will be wayyyyy off. In addition, try and keep your rod height down at about 1.8m high and try and limit your tilt to 30 degrees. This will achieve the best results in our experience. And remember to calibrate your tilt sensor on a regular basis. Make it compulsory to calibrate the sensor before each job. It only takes 1 minute.
In summary TILT has revolutionised surveying in the same was as reflectorless Total Station technology changed the way we felt when we took our Total Station out of its box. If you have not tried it yet, take our advice and jump onboard. For reference we use a combination of Stonex S990A, CHCNAV I73 and DATRONIX D20 GNNS systems. These things cost no where near the €30k of yesteryear.