When is Enough Data Enough?

The age old question that has always plagued surveyors is How much data is enough data?. While too much data can be a burden for downstream users, the problem of too little data is even worse. Gathering too much data increases field time, processing time and can affect the schedule for the project, especially if the end user has to filter out unneeded information. Not having enough information shortens ever tightening deadlines and budgets. This is especially true when youre forced to go back to the site and collect more information. Anytime you have to return to the job youre losing money. Remobilization, travel time, added processing time, etc. continue to drain profits from your business.

How do you combat this issue? The most critical issue is communication. It starts with communication between the surveyor and his client. You cannot determine what type of data and how much you need to gather until you understand what the data will be used for. Quite often the client themselves are not sure what their needs are. The best way to solve this is with a kick off meeting prior to the work commencing. Its even better if you can hold this meeting prior to putting together a proposal for the work. I have a set list of questions I ask any prospective client prior to preparing a proposal and then I go over these questions again at the kick off meeting to confirm nothing has changed.

What are you using the data for?
What is your end product or deliverable?
What format do you need the data in?
What is your time frame?

These four simple questions can go a long way in helping you determine what is required from your end. Be advised your client may not necessarily have the answers to one or more of these questions. While this can be frustrating, it is important to be patient and try to gather as much information as possible with follow up questions.

In many instances your client may not be aware of the benefits of having scanned data as opposed to more conventional coordinate files. This can also be an opportunity to showcase your firms knowledge and experience. Often times it provides you with an opportunity to showcase your abilities with a technology. And finally, it shows a willingness to work as a partner in the venture and not just as a subcontractor.

The value of good communication does not end with your client. You must communicate clearly with your staff on what will be required and how you want them to generate your end product or deliverable.

So now we get back to our original question, how much data is enough? If you have established how the data will be used and what it will be used for, this part should be easy. If youre scanning for architectural reconstruction, then you want to make certain you capture data to a resolution fine enough to accurately record an image that reflects the same level of detail that the scanned object was built to. A building with less detail will require fewer points, while a building with fine intricate detailing will require more.

If youre using scanning as a means to capture topographic information you can probably thin out certain areas. If youre contour interval is to be in the half meter range on open ground, you can probably set your resolution for 1/3 to 1/4 that amount and still achieve the desired level of detail. When in doubt, always err on the side of too much data. Most of the software available in processing will decimate, or thin out your data. Be very careful when doing this as you dont want to thin it out too much. A good practice is to always back up the original data and use a copy of your file to thin out.

Schedule a meeting with your client prior to delivering the final product. Show them what you have and make certain that what you are planning to deliver is going to suit their needs. You should be prepared to offer multiple options, a version of what you consider to be the final deliverable and one dataset of the total data if you have decimated it or if you havent a smaller decimated dataset.

Each project will be different based on your clients requirements and the type of work youll be doing. So if you really want to know when is enough data enough, learn to communicate clearly with your clients, your staff and most importantly your financial advisor, as successful management of understanding project requirements will lead to financial profitability.

About the Author

Rob Mellis

Rob Mellis ... Rob Mellis has been working as a Land Surveyor for more than 30 years. He is licensed in the State of Florida and has experience in performing boundary, control, construction and design surveys. He has worked for the Florida Department of Transportation, as Field Party Chief and Head of Survey Computations for Right of Way Mapping Section. For the past 10 years he has worked for Bentley Systems as a Senior Survey Consultant, responsible for consulting, training and marketing the Bentley Civil and GeoSpatial product lines. Most recently he joined Bechtel as an Area Surveyor on the Dulles Corridor Metrorail Project.
Contact Rob Article List Below