Surveying because you can…


Surveying because you can…

Tom measuring from lamp-post to office front door!

A light hearted one this time….

You know when you walk past something everyday and it just looks wrong? For the last few months I have walked past a sign stuck to a lamp post which says “WORKSHED 50m ahead”, which, in itself isn’t offensive but the navigator in me blatantly knows that it is definitely NOT 50m.

Days go past and each time I past the sign a little tick starts occurring and I find myself cringing, but what do you do? Luckily for us at The Carto Group, we have always have a bit of survey gear around thanks to our Lead Surveyor, Tom Ridgway being in the office.

On this day, Tom had been out doing some rectification work (getting the correct real world coordinates to make sure a model could be put accurately in a geospatial context) and we had a Trimble R8 hanging about… Tom and I set out to calm my curiosity.

The Trimble R8 is a great bit of kit, allowing 440 channels (think of a channel as a satellite signal – 440 channels allows the unit to ‘lock on to’ and search for up to 440 satellite signals simultaneously for improved accuracy and speed of survey) and is lightning quick, thanks to all those channels getting a good fix. With a precision of 8mm, making sure we got the measurement right was never an issue….though being close to the wall was.

Little known fact – in built up areas GPS signals (radio waves) can be blocked (called shadowing in the trade) and this means getting a reliable bit of equipment is important. This is why your mobile phone can sometimes be a bit strange in city centres!

Tom concentrating on getting his measurements correct

We managed to get a good fix and within 10 minutes we measured the distance, it was not 50m and my curiosity is now quenched.

….the measurement? That was 38.5 metres. Remember that next time you walk past the lamp post on London Road, Swindon which has the sign and try not to let it bother you that it is wrong.

Are your building, land or asset measurements correct…?

Thanks for reading,


CTO & 3D Geospatial Expert, The Carto Group

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Dave Rowe

Dave Rowe, Principle Developer, The Carto Group.

About the Author

Dave is an open data advocate, always looking to deliver as much value as possible from clients data.

Microsoft Certified in cloud Azure stacks, Dave is an awesome GIS Software Engineer that takes web GIS applications to the highest level.

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