## Converting Decimal Degrees to Degrees Minutes Seconds

Often we are supplied with coordinates in decimal degrees but need to use Degrees, Minutes, and Seconds instead. Luckily, there are several solutions that you can use, here is a simple coordinate converter tool that I use.

## Using Google Earth to obtain NGS CORS site information

Every now and then I come across some little utilities that help to make things easier while working in the field and these pages are mainly my way of sharing them with others while creating a go-to place where I can easily find them when I need them.

Here is a Google Earth file that that contains locations and basic information about all of the National Geodetic Survey (NGS) Continuously Operating Reference Stations CORS. Saving you time from searching for CORS stations in your area and finding out what sampling rate they record GPS data at.

## GPS Calendars

GPS or GNSS Calendars are different then traditional calendars that most of us are used to working with, yet they are pretty common these days due to the increased use of GPS equipment. Yet there is never one around when you need one, so if you find your self doing a lot of GPS field work like myself then you may notice that you will working in Julian Days & GPS Weeks frequently so will want to print off your own copy or use an online utility to help you out.

For those new to GPS or GNSS Calendars: Julian Day is simply the numeric number of the day in that given year, example March 5th of the year 2013 would be the 64th day of the year with a julian day of 064 and a GPS week of 1730. The GPS Week # would be 17302 (the # 2 on the end represents Monday from the formula Sunday=0, Monday=1, Tuesday=2, Wednesday=3, Thursday=4, Friday=5, Saturday=6).

Now one can easily calculate this info but I find it quicker to just resort to reference pages or use online utilities and here a few that I use:

– 2013 NOAA GPS Reference Calendar or Canadian Spatial Reference System GPS Calendars (provide PDF versions but do not yet have a 2013 version available) for printing reference pages

– Here is great little online interactive GPS calendar utility that I often use, simply click on a date in the calender and the utility will show you the corresponding Julian Day, GPS Week and GPS Week Number for various years.

## Converting between UTM, MTM and LAT/LONG

Geographic coordinate systems enable us to spatially locate features on the Earth using specified set of two dimensional numbers. The coordinates of each feature represent the horizontal position (and sometimes vertical position when elevation is available) of it and one of the most commonly used coordinates is Geographic with values of latitude, longitude. However many different coordinate systems can be used to map the same area depending on various factors such as map extent, scale, end user etc. Therefore we often find in Geomatics that we can have data from different coordinate systems that we need to use together spatially in one reference system.

I am sure that most of us have run into times when we have features that have defined coordinates of one system that we need to use with a different one. (E.g. your map is in UTM (Universal Transverse Mercator) but you have been given GPS points in Lat/Long).

If you ever find yourself in need of quickly getting values converted from Geographic to UTM / MTM (Modified Traverse Mercator) or UTM / MTM to Geographic then here is a a free online geographic coordinate convertor tool that I often use provided by Canadian Spatial Reference System

## Real Time Kinematic (RTK) Surveying Guidelines

Over the past decade Real Time Kinematic (RTK) surveying with Global Navigation Satellite Systems (GNSS) has become common practice in geomatics. RTK surveying can allow people to achieve relative positioning with centimetre (cm) precision, however there are several important factors that need to be considered and thus a need for a good guide of best practices (equipment calibration, errors, multipath, geometry, etc.). Therefore Natural Resources Canada (NRCan) put together a new set of guidelines for Real Time Kinematic (RTK) Surveying.

## Where will your Geomatics Career Bring You?

### “Should you Specialize or Diversify?”

Something many of us in geomatics often come across in our careers is whether or not we should be specialized on a specific geomatics aspect (like a certain software or skill set) or should we diversify and become competent in a multitude of geomatics related disciplines.

One particular problem with being really specialized in something is that although you become an expert in something you can often be too focused, and potentially closing other doors or limiting possible career paths. When you diversify you can still become specialized in things but at a lesser extent yet work with more components of the industry.

When I started off my geomatics career I thought it was better to become specialized in a particular trait and that would maintain my career path. Well that did work out pretty good for a few years, and I became very efficient in one aspect of geomatics (orthophotography and imagery analysis).

However one day I realized that I was focused only a narrow spectrum of the skills that I had worked so hard to learn. As a result I was losing many other skill-sets that I had developed.

### “My career and has allowed me to be involved in many projects that go well beyond what my education prepared me for.”

Since then I have almost gone to the other extreme and have become diversified, experienced and well rounded with a multitude of geomatics skills which has in turn often provided me an edge in my career and has allowed me to be involved in many projects that go well beyond what my COGS education prepared me for. And I find that it makes for a more interesting career when your job allows you to combine a multitude of different geomatics aspects together.

Now, everyone is different and the great thing about the Canadian geomatics industry is that there are plenty of opportunities to Specialize or Diversify, so perhaps you should consider ‘Where will your Geomatics Career Bring You?’ when you are sending out your resumes. Do go out there, network and get advice from others, But do what best suits your career aspirations.

I have been fortunate enough to be able to travel all over North and Central America with my jobs over the years and recently I came back from doing some field work in Newfoundland & Labrador and since last month’s GoGeomatics theme was “Canadian Surveying & Surveyors” Jonathan asked if I could share some of my photos from the trip with the GoGeomatics Magazine.

The five week trip involved GPS and total station survey work in many remote scenic locations with pretty decent weather (only a few days of snow). I have included a few photos here, but you can find more on my Flickr photo account or on my blog where I frequently add photos and information about my trips and projects that I have been involved with.

Note: This post was picked up by GoGeomatics and also published in their digital magazine

## Precise Point Positioning GPS Processing

Sometimes when doing GPS field work I will often require a way to double check my own GPS Processing work or am sometimes too far from an active control network to tie into. Using Precise Point Positioning or PPP service in these situations has often come to my aid,  especially on jobs in Nunavut or in Northern Ontario.

Natural Resources Canada’s Canadian Geodetic Service provides a free online global GPS processing service called Canadian Spatial Reference System – Precise Point Positioning (CSRS-PPP), where you can process files containing RINEX (common Receiver Independent Exchange Format that is used to exchange GPS data between various software and hardware) observations from either a single or dual frequency receiver in either static or kinematic modes. The service is free but does require that you sign up to obtain a username and password to gain access.

Once logged in, you upload your GPS file and basic info, then you will receive an email containing corrected coordinates (latitude, longitude, ellipsoid height) in either NAD83(CSRS) or the ITRF reference system. It also applies the HTv2.0 height transformation and produces orthometric heights compatible with CGVD28 elevations to your data.

PPP results generally are more accurate when recorded over a span of several hours, so I tend to let my receivers run longer if I know that will be using PPP.

“PPP accuracy improves with the length of the data collection period. A minimum period of good quality GPS data is required to permit convergence and resolving ambiguities which in turn can improve the accuracy of the entire dataset. The minimum period and the accuracy attainable will depend on the type of GPS equipment, the site (multipath, obstructions) and atmospheric conditions. Extending the data collection past this minimum period should further improve accuracy, but more so with dual-frequency receivers than with single frequency”. See http://www.geod.nrcan.gc.ca/products-produits/ppp_acc_e.php for more information.

The Canadian Geodetic Service have also created a PPP Direct utility for Windows 7 (note: I have not tested it yet) where you can Submit your GPS data for PPP processing without logging on to the web site. The PPP Direct utility lets you ‘drag and drop’ RINEX files onto an icon where it is then immediately submitted for CSRS-PPP processing (so an internet connection is required).

The login to begin PPP processing or to download the PPP Direct utility installation file is http://www.geod.nrcan.gc.ca/online_data_e.php and a detailed PPP handbook covering all the basics of the service can be found here http://www.geod.nrcan.gc.ca/userguide/pdf/howtouse.pdf

## GIS Mobile Mapping

During the fall of 2003, the Applied Geomatics Research Group (AGRG) added eight weather stations to their already existing weather network. The weather stations designed by Campbell Scientific were spread through out the Annapolis Valley (Nova Scotia) region from Digby east to Grand Pre. The data from these weather stations needed to be periodically collected and they also needed to be inspected from time to time for any maintenance issues. Therefore, as graduate students we were each asked to create a mobile mapping application for ESRI Arcpad that could be used with a Trimble Geo Xt hand held GPS unit that could aid in the collection of the weather data.

Included below on this page is the report written for this project, a presentation that covered all aspects of the project and more general information and links about GIS mobile mapping. The report includes all code used in designing the ArcPad application (visual basic, XML etc). The presentation was presented at COGS in Lawerncetown, Nova Scotia during the fall of 2003. The existing AGRG weather station network now consists of 14 tripods and 1 tower setup (as of Aug 2004).

Basic overview of Mobile Mapping

When you combine global positioning systems (GPS) and geographic information system (GIS) technology together you get a powerful tool better known to most in the Geomatics industry as Mobile Mapping. This combined technology allows users to visualize information with existing digital data, record new information exactly directly at the source, and interact directly with the world around you.

Over the past few years the main process of collecting field data included gathering and using information with a paper-based process that quite often involved a lot of data entry without access to real-time information. The recent advancements in GIS and GPS technologies have changed many of the field-based information gathering processes and increased the efficiency and accuracy with which field users collect and use spatial information.

There are several different software and hardware combinations suitable for mobile mapping tasks that are currently available and range from simple inexpensive to more complex setups. This page will use ESRI ArcPad as an example due to the relative experience I have had with this over the past few years. But do keep in mind that there are many more different ones out there and one should experiment to find the setup that best fits their project needs.

ESRI ArcPad software combines database access, mapping, GIS, and GPS integration when you are in the field via a handheld computer device. The main advantage to this is that you can incorporate your existing data such as database, vector and raster images along with the data that you collect. The following are some of the many functions that are possible with mobile mapping:

– Move around your map with navigation tools including zoom and pan, and center on the current GPS position.