The other day I was working in Ekahau Site Survey and ran into an issue that I thought could use some improvement. I took to Twitter to voice my #ESSRequest. Rather than being met with affirmation, I had apparently committed a cardinal ESS sin by setting the scale of my project using the opening to a commercial doorway. I am formally trained in the ways of the ‘hau and I could have swore it was suggested to me that measuring a commercial doorway was a suitable way to set the scale within a project (as long as you actually knew the real measurement of course). After reading the reminders of my idiocy, I came to the conclusion that what my peers were saying did actually make sense. It has been suggested that measuring a known “larger” distance will in fact yield a more precise scaled project. After explanation, it makes perfect sense to me. Trying to be precise within a small area creates room for error. A small mis-measurement of pixels could render your project flawed and the error could grow exponentially as your survey grows. Setting the scale of your project should be done using a known length of something much larger, such as a long corridor, wall, or something of the like.
It sucks being wrong, but I will admit my shortcomings. I am a certified “Expert” but I do come up short sometimes. It is my belief that an expert should always have an open mind and should always be willing to learn new things, even if it is something that he or she “should” already know. In this particular situation, I was re-evaluating what I “should” have already known on my commute to work. Even though I do agree with the #NoDoors policy, it did challenge me to think even deeper about the approach we are to take when scaling our surveys. If measuring a small, “inconsistent” feature such as a doorway within a map could skew your survey data into the toilet, what would the impact of being 5 inches off your line doing a continuous survey be? The center of a zoomed out hallway looks a lot different than a zoomed in hallway within ESS. What if you inadvertently walked diagonally off your line 10 inches in a large open space? Simply zooming in and out between stop and go measurements could make a massive impact to your survey. I know I have done surveys where I zoomed in on the start of a continuous survey and found that I was actually a couple of feet off of my starting mark. Being zoomed out might have you think you are up against the end of a hallway, while zoomed in will show a much larger gap between the wall and your starting point. How do we make our surveys as accurate as possible? Garbage in is garbage out, right? The only way I can think of to get absolute precision is by using a GPS. I have no real world experience using a GPS with ESS but I would think GPS signal within a building is somewhat of a challenge. Perhaps I need an ECSE refresher?
I think the answer to these questions were perfectly summed up by my colleague in a DM while I was conversing with him about this exact issue:
There is no way you can get everything precise within your survey. There are going to be inadequacies and errors. Some of the errors will be inconsequential and some will have a serious impact on your finished product. The best thing to do is use the knowledge that you have to minimize mistakes and make good decisions based on training and experience. Is running a second survey for comparison a good idea? Validation is key, right? Sometimes ultra-precision isn’t practical. Time is money…
At the end of the day we all want to do a great job with our work. We will all make mistakes, even us “Experts.” We will all learn from those mistakes (hopefully). We also need to remind ourselves there is more than one way to get to a suitable solution and delivery is key when putting someone on notice about their ill advised practices.
I still have new questions about the precision aspects to surveys. I am in no way disqualifying the usefulness of ESS. I couldn’t do my job and be successful without it. The good people at Ekahau have created a truly EXCEPTIONAL product and are building on its greatness. Ekahau Site Survey’s greatness is second only to the incredible people who make and teach it. I look forward to each opportunity I get to use the software and I consider myself one of the lucky ones that was able to sit the Ekahau Certified Survey Engineer class. I’m sure the vast majority of ESS users are self taught or are unable to attend an ECSE class for any number of reasons. If you are afforded the opportunity, I STRONGLY recommend taking an ECSE class.
Keep up the great work Ekahau!