GPS / PDA / Data Capture?

[Paul Barton]

My tuppence worth:

 

Hardware:

I use a Getac GPS PDA for data capture using software that requires the Windows operating system: http://en.getac.com/pdf/PS535F.pdf. It's a good little unit - the GPS is fast and pretty accurate (not sub-metre though) and it's small and light so you can stick it in your pocket when you need both hands free.

 

I have recently bought an iPad Air with a Lifeproof waterproof case. I really like the bigger screen - makes it easier to view plans and enter information on to spreadsheets if you use them. The 'numbers' app has some great features such as forms that complete each column, and drop-down menus.

 

Software:

For GPS data collection I use Digiterra or Pocket GIS (but I'm not very good at PocketGIS yet). I think Digiterra is about £750. It comes with a desktop version which is basically a GIS - so you can manipulate data, create maps, export as different formats...

 

I am looking at some cheap options to turn the iPad in to a GPS data collector. The best looking one I have found so far is GIS Pro (GIS Pro & GIS KitGarafa | Garafa). I haven't yet bought it so can't give a proper review, but it appears to do all the things I need. I particularly like that it can cache aerial photos from Google Maps etc so you can use it offline in the field. You can also load in your own geo-referenced site plans if you need to.

 

Hope that helps.

 

Paul

[Tony Banner]

Hi all, am looking at pear technology for my first investment in this kind of kit, budget about £1500-£2000 for software, data capture device ( tablet but not an Ipad, am sick of apple ) and gps, that should be enough shouldn't it? I'm not as computer savvy as some of you, who are writing lines of code and the such, and pt mapper pro looks pretty straight forward to me. Someone tell me if am wrong please, am just looking for minimum fuss really I'd rather spend a bit more money and get it right first time round.

 

Any help or advise appreciated

[daltontrees]

I am led to believe PT Mapper is a magic wand. It and PGIS is £1250.

[aitch]

Accuracy should be a major factor. I've tried to revisit some old surveys done with Garrmin gps and it was impossible to work out which tree was which. Valleys and tree canopy play a big part and as i understand it to get the accuracy i want is unafforable on my shoestring budget.

[daltontrees]

Accuracy should be a major factor. I've tried to revisit some old surveys done with Garrmin gps and it was impossible to work out which tree was which. Valleys and tree canopy play a big part and as i understand it to get the accuracy i want is unafforable on my shoestring budget.

 

There's no right answer. I was working last week with a brand new Juno and an oldis Geo on the same survey. The Juno was preciser but inaccurate, the Geo wqas imprecise but accurate. When you're in amongst trees and buildings it is just not possible for a device to interpret compromised satellite signals and produce an accurate and precise position. It's like trying to find out where someone is shouting from in a canyon.

[10 Bears]

Thanks everyone for some really great input here, and there is certainly some hardware I will now investigate.

 

Comments about accuracy being difficult are always associated with handheld GPS and there are only 2 solutions. The first is buy some kit with the opportunity to affix an external aerial (this again gets into the more expensive realms), or second, stay in the surveying location for a longer period. On the Trimble Terrasync software in the GPS - you will see a number that confirms how many 'hits' you have had from the satellites (its in the ribbon at the top as I recall). I believe if you stay put until you have c.30 hits then accuracy is greatly improved. I don't know if other softwares show this hit rate - but I would guess so.

 

The only issue is, if you are surveying a lot of trees, that having to wait for the required number of hits will increase the overall length of the survey... Cant win them all!

[Adam M]

I've got a download demo of Pear Tech's software which I will comment on over this weekend. I've also been working on a MS Access database and am starting to see the light with it I think, although quite a way to go with it. Once that is "done" though, it'll be good for the foreseeable future.

[10 Bears]

Just an update - I came across this article which discusses a submetre GNSS receiver specifically for those of you using iPad/iPhones Geneq Introduces Sub-Meter GNSS Receiver for iPad, iPhone : GPS World

 

I don't have either so I've not spent much time looking into this, but its currently in the states and should be either released over here or possible to direct import.

 

Adam M - how did you get on with Pear Tech? I'm interested to know. I've also PM'ed you - could you check?

[daltontrees]

Thanks everyone for some really great input here, and there is certainly some hardware I will now investigate.

 

Comments about accuracy being difficult are always associated with handheld GPS and there are only 2 solutions. The first is buy some kit with the opportunity to affix an external aerial (this again gets into the more expensive realms), or second, stay in the surveying location for a longer period. On the Trimble Terrasync software in the GPS - you will see a number that confirms how many 'hits' you have had from the satellites (its in the ribbon at the top as I recall). I believe if you stay put until you have c.30 hits then accuracy is greatly improved. I don't know if other softwares show this hit rate - but I would guess so.

 

The only issue is, if you are surveying a lot of trees, that having to wait for the required number of hits will increase the overall length of the survey... Cant win them all!

 

Recent experience suggests that GPS can't betrusted even when the signal is 'aged'. Surveying last week I established a location in clearing, then watched for 5 minutes as the cursor location (stated by the machine as HDOP 0.8m) wandered off across the clearing, into the trees, back into the clearing, across it and out the other side.That was with the Trimble immobile on a tree stump. According to the base map which had a hypothetical development layout on it, the sub-metre position had travelled 25 metres.

[daltontrees]

Just an update - I came across this article which discusses a submetre GNSS receiver specifically for those of you using iPad/iPhones Geneq Introduces Sub-Meter GNSS Receiver for iPad, iPhone : GPS World

 

 

Interesting, but if I read it right you need an iPad adn this blue thing that communicates with it by bluetooth over a range of 15m. That could get cumbersome in practice. Unless you could mount the blue thing on your head. That would leave hands free for the iPad. Might draw a few funny looks though. And/or cook your brain.