FAQs

FAQs

Surveying

HOW DO I CONVERT NGVD29 TO NAVD88?

HOW DO I CONVERT OLD SURVEYS TO NAVD88?

MY HANDHELD GPS GIVES ME BAD ELEVATIONS. WHY?

WHAT KIND OF GPS RECEIVER DO I NEED?

CAN I USE MY SINGLE FREQUENCY SURVEY GRADE GPS RECEIVERS FOR ELEVATIONS?

IS THERE A MORE COST-EFFECTIVE USE FOR GPS SURVEYING?

Real-Time Network

WHAT IS C4GNET.XYZ REAL-TIME NETWORK?

Louisiana Spatial Reference Center (LSRC)

IS NGVD29 THE SAME AS MEAN SEA LEVEL?

WHY DID WE SWITCH FROM NGVD29 TO NAVD88?

WHY DID THE ELEVATIONS CHANGE WHEN WE SWITCHED TO NAVD88?

DID WE SINK THAT MUCH?

WHAT IS THE CONVERSION FROM NGVD29 TO NAVD88?

Can’t I use CorpsCon to convert survey data from NGVD29 to NAVD88?

WHAT IS A DATUM AND AN EPOCH?

OK, AGAIN, WHAT IS AN EPOCH?

WHY DOESN’T MY BENCHMARK SHOW UP ON THE NGS WEBSITE?

WHAT DOES THIS 2004.65 EPOCH MEAN?

WHY IS THE ELEVATION ROUNDED TO THE 0.1 FOOT ON THE NGS DATASHEET?

IS GPS MORE ACCURATE THAN LEVELS?

WHAT IS MLLW AND HOW DO I USE IT?

WHO ELSE HAS SUBSIDENCE PROBLEMS (TEXAS?) AND WHAT ARE THEY DOING ABOUT IT?

Continuously Operating Reference Stations (CORS)

HOW CAN I GET AN ACCURATE, UP-TO-DATE ELEVATION?