Imagine that the location of something on your map is not there in reality? It happens all the time. Think about navigating to a place, while you are driving. Have you ever discovered that there was an error in the location? OK. The point is made. What are the reasons that this happens? Let’s list potential ones:
The location is based on an outdated survey plat.
“What’s a survey plat?”, you ask. This is something that most people do not think about – the source of the location of a place, building, etc., and how it is described. How does that happen? You may not know that originally, a surveyor was standing on that plot of land, and used instruments to accurately measure the latitude and longitude coordinates of that site, and the building on it, based on a certain coordinate reference system.
- If the plat is signed and stamped, it means that surveyor was a registered land surveyor. Being registered, a surveyor’s credentials are assured. Legally, the surveyors “plat” (mapped location(s)), is a representation with legal descriptions of where a place is, and it’s name, and much more. The surveyor’s plat is assured to be accurate by the surveyor’s signature and stamp. This is an assurance sign of integrity about the information contained on the plat.
- The survey was completed and submitted to the local authority’s office of records, or quite possibly as part of a permit to build. This activity begins the origin of the location of that place, and all of the descriptive information about it.
- If the building permit is approved, and the building is built, as described, then location quality is assured. However, errors happen. Sometimes, after the building is completed, the survey is not updated with the “as-built” location of the building. There can be many reasons for this, but sometimes the old survey is used instead of the latest updated survey by mappers.
Mappers should always check for the latest survey.
The place was mapped wrongly, by the original mapper. This can be due to a variety of reasons.
- The original mapper could not translate the surveyed location to the map. Perhaps the mapper did not have the basic skills for locating buildings on the map based on the survey. This requires more steps than most people think.
- The mapper might not have been skilled in accurately placing the surveyed location on the map that was being used – we call that the basemap or the reference map.
- There may have been a coordinate reference system alignment problem. This is a very common situation. To achieve spatial alignment, the mapper must have the understanding of geodetic principles and coordinate reference systems – we will call that “spatial referencing” for now. When mapping exact locations of anything – especially where precise location is required – mappers need to have the knowledge and the skills to place locations on a map with accuracy.
- Sometimes, the basemap is in one coordinate reference system and the building survey is in another. The mapper needs to align the two by doing some operations that transform the building location to the same one as the basemap being used for mapping.
The metadata is not up to date. Maintaining the data behind that location is very important. If it is not updated, people are at a minimum inconvenienced and disappointed – but, sometimes, this can be life or death.
Later on, after the location is mapped, sometimes change happens!
- The details about the business have changed. Maybe the owner moved the business. Perhaps the business failed, and some other business bought or leased the building. This means that the “data” describing the location was not updated.
- Inconvenience is one thing. Don’t you hate driving somewhere, only to find that it isn’t there anymore? You think, “Gee, I really had my tastes set for that latte that was so yummy that I got at that coffee shop before!” You drove all the way to this location and the map let you down. Rather, the people who maintain the data let you down. Out of date data impacts people in a variety of ways.
- A more serious implication – it can mean the difference between life and death, where precious seconds count. Emergency response can be impacted. When first responders depend on a map to help them reach people in distress, or respond to a fire, they depend on up-to-date information. If the map data is not kept up to date, the first responders could have issues that can cost precious time. Imagine that the first responders need to locate the owners of the building to get into it. Imagine that there is a person inside and the first responders cannot penetrate the building to find the person who has become unconscious since the call was made.
