INTERSECT~(TM): Which Map Is Correct? If seeing is believing, then which map is correct, the survey map or the GIS map?

摘要

GIS JANET says ... A mong my first responses to the question "Which map is correct" are "Why are they different?" or "Maybe they are both correct." But I usually know why they are different, and sometimes I can even guess how it happened. However, the question is a valid one that I hear quite often. It seems that, no matter where I travel, a surveyor will say, "You know what really bothers me? It's the way GIS represents the surveyor's work. Sometimes it's accurate and sometimes it's not. It's confusing when my client shows me a map that has been created from a GIS and wants to know why my survey, the one they paid me to do, and the 'map' don't agree. I don't know what to say." SURVEYOR RANDY says... At last, an easy question to answer. The survey map is the correct map. Seriously, except for rare exceptions, if a county GIS site and a survey plat have significant differences for a particular property boundary, the survey plat accuracy should be significantly better than the GIS representation. Any current survey map signed and sealed by a professional land surveyor should, without question, be the correct graphic depiction of a particular parcel of land. I have no desire to beat up the GIS cadastral mappers. My staff and I use GIS property information successfully all the time. But we rely on the GIS information only to the extent that is reasonable, because we realize that GIS property mappers have some limitations. A couple of their limitations are the data (deed descriptions and survey plats that are public record) that they have available and the time they can allot to solving and piecing together the property jigsaw puzzle.