What is wgs84 datum

The radio waves transmitted by GPS satellites and trilateration enable extremely precise Earth measurements across continents and oceans. Geodesists could create global ellipsoid models because of the enhancement of computing capabilities and GPS technology. WGS84 is made up of a reference ellipsoid, a standard coordinate system, altitude data, and a geoid.

Hi I just want to understand, how geodesy can be used as a basis for establishing datum? Hi, Your page is quite informative. I am clearly trying to do something way out of my league. It seems I seem an astronaut and a cartographer for this one!

How does one find the proper Lat and Long conversion? Consumers are using GPS in many personal devices, and keeping the programming and mapping requirements simple is key to their success. Excessive accuracy is not necessary when it comes to these devices, so a meter or two variations is perfectly acceptable. That is why the original WGS 84 reference frame is programmed into these devices and is still utilized for most large-scale mapping needs.

But what happens when the mapping needs to be more precise? The need for precise data collection gets us back to the surveying community. Locations derived from data collected in local coordinate systems and transformed to WGS 84 values will be subject to characteristics and distortions potentially affecting the local system. This leads your subject data down an uncertainty path that may not be acceptable to your delivered product.

These accuracies are not usually acceptable in the surveying world and hopefully not in most GIS base-layer situations either. One of the best solutions for high-accuracy data collection that will be more compatible with GIS database needs is to start your data collection with ITRF-based points, if possible. This method keeps your data consistent with current WGS 84 reference frame parameters and will fit seamlessly into most systems as required.

Most hardware and software systems allow for its implementation as a coordinate system option and is just as easy to use as our normal NAD83 based systems.

Think back to your early math class days; we spent many hours learning trigonometry functions by hand before we were turned loose with a calculator with sin, cos, and tan buttons. Learning longhand what was being produced helped us to understand how those complex calculations were completed.

The good news for geographic data users in the United States is that the National Geodetic Survey NGS is working on a new datum that will incorporate radical new changes in combining horizontal and vertical datums.

Visit the NGS website for more information. The initial framework sounds very robust and user-friendly, so keep your eyes and ears open for more details as they develop. The problem sometimes with technology is that it moves forward so quickly that good innovations get passed over due to previous acceptance and reluctance to upgrade such as Sony Betamax, Microsoft Zune, etc. This has been true with geodetic datums and the introduction of GPS for mainstream use. It will be an age-old issue, but I look forward to better and brighter days ahead.

If you enjoyed this article, subscribe to GPS World to receive more articles just like it. The WGS 84 reference frame is defined by the geocentric positions and velocities of the U. While GPS observations are the primary inputs to the process, the ground station coordinates and velocities define the reference frame axes.

These coordinates and velocities are calculated by NGA and provided to the Air Force to used in the computation of the navigation message broadcast by the satellites. Thanks for the additional information; I appreciate the further clarification of the reference frame.

And if the receiver is using SBAS eg. WGS G is fixed at Thanks for the follow-up and the comments. While trying to keep this topic under a small novella, both you and Scott made great additional points. I do want to emphasize as a Federal employee, until arrives, I am held to provide data, share data in the latest NAD83 epoch.

Like to hear comments — great topic and great magazine. Your behavior appears to be a little unusual. Please verify that you are not a bot. Follow Us. This continuous ground movement means that even in the absence of earthquakes and other localised land movements, WGS84 coordinates are constantly changing. These are often referred to as dynamic or kinematic coordinates.

Therefore it is important that coordinates in terms of WGS84 have a time associated with them, especially where the best levels of accuracy are required. Note: There are multiple realisations of WGS Each of these realisations is a separate datum.