Nad83 vs wgs84

The North American Datum of 1983 (NAD 83) is the horizontal control datum for the United States, Canada, Mexico, and Central America, based on a geocentric origin and the Geodetic Reference System 1980. This datum, NAD 83, is the current geodetic reference system. NAD 83 is based on the adjustment of 250,000 points, including 600 satellite ...

May 29, 2007 · The latest version of NAD83 and WGS84 frames are specifically named NAD83 (CORS96) and WGS84 (G1150). Thus, when the receiver tells us that the computed coordinates using GPS observations are referred to the WGS84, they actually mean WGS84 (G1150). On the other hand, if we use CORS coordinates data, or the OPUS service, the NAD83 reference ... WGS84 frames are specifically named NAD83 (2011) and WGS84 (G1674). Thus, when the software tell us that the computed coordinates using GPS observations are referred to the WGS84, they actually mean WGS84 (G1674). On the other hand, if we use CORS coordinates data, or the OPUS service, the NAD83 reference frame to whichI am looking for a function to convert these NAD83 coordinates to regular GPS lat/lon. ... / Missouri East) to 4326 (WGS84 - World Geodetic System 1984, used in GPS) transformer = Transformer.from_crs( "epsg:3602","epsg:4326",always_xy=False) #empty lists to hold converted x y coordinates lat = [] lon = [] #loop through columns …Feb 12, 2009 · Projection basics the GIS professional needs to know. Coordinate systems , also known as map projections , are arbitrary designations for spatial data. Their purpose is to provide a common basis for communication about a particular place or area on the earth's surface. The most critical issue in dealing with coordinate systems is knowing what ... That’s why the U.S. National Geodetic Survey is now modernizing its National Spatial Reference System (NSRS). They will replace NAD83 as their national geometric reference system with the North American Terrestrial Reference Frame of 2022 (NATRF2022). This update was originally planned for 2022 but has been delayed until …No, WGS84 is not a vertical datum. It is a horizontal datum used for latitude and longitude coordinates. However, it can be used as a reference level for vertical measurements. What is WGS84 vs NAD83? WGS84 and NAD83 are different datums used for different purposes. WGS84 is a global reference system used by GPS and …The primary distinction between these systems lies in the ellipsoid they use. NAD83 employs the Geodetic Reference System 80 (GRS80) ellipsoid, while WGS84 utilizes the WGS 84 ellipsoid. Although the dimensions of these ellipsoids differ slightly, they play a crucial role in accurately determining positions and coordinates on the Earth’s surface.

NAD83. WGS84. Longitude. 134° 21' 49.21 " 134° 21' 55.59 " 134° 21' 55.66 " Latitude. 58° 22' 3.30 " 58° 22' 2.13 " 58° 22' 2.15 " All three coordinates above identify the same physical point on the Earth's surface, but the seconds value varies. This is due to the different ellipsoids associated with the datums. The reason why this ...NAD 83 and NAVD 88, although still the official horizontal and vertical datums of the National Spatial Reference System (NSRS), have been identified as having shortcomings that are best addressed through defining new horizontal and vertical datums. Specifically: NAD 83 is non-geocentric by about 2.2 meters. NAVD 88 is both biased (by about one ...Depending on one’s location, coordinates obtained using NAD83 could be hundreds of meters away from coordinates obtained using NAD27. The World Geodetic System of 1984 (WGS84) is identical to NAD83 for most practical purposes within the United States. WGS84 is the default datum setting for almost all GPS devices.WGS84 frames are specifically named NAD83 (2011) and WGS84 (G1674). Thus, when the software tell us that the computed coordinates using GPS observations are referred to the WGS84, they actually mean WGS84 (G1674). On the other hand, if we use CORS coordinates data, or the OPUS service, the NAD83 reference frame to whichDatum is an older term. The concept of a datum is included within a geographic coordinate system. A geographic transformation is always defined in a particular direction, like from NAD 1927 to WGS 1984. Transformation names will reflect this: NAD_1927_To_WGS_1984_1. The name may also include a trailing number, as the …Convertir en NAD83 convertit les coordonnées en système NAD83. Les coordonnées d'origine peuvent être dans le système: UTM, GPS / WGS84, NAD83 et d'autres systèmes populaires. En option, vous pouvez sélectionner le système en entrant le code EPSG. La base de données du registre EPSG comprend plus de 1000 entrées.HTDP – Horizontal Time-Dependent Positioning. HTDP is a utility for transforming positional coordinates across time and between spatial reference frames. *** HTDP should NOT be used to transform between NAD 83 realizations (2011, NSRS2007, HARN, etc.). It will not give correct results.How do the horizontal datums differ? Which should I use? What is HARN or HPGN? What are NGVD 29 and NAVD 88? Why did NGS change from NGVD 29 to NAVD 88? What is the relationship between the geodetic vertical datums (NGVD 29 and/or NAVD 88) and the various water level/tidal datums? What is WGS 84? Does it change? Answers...

Should you transfer or roll over your retirement accounts? See more about transferring your retirement accounts at HowStuffWorks. Advertisement There were rumors of layoffs at your...The latitude and longitude location in the NAD27 datum differs from NAD83 or WGS84. This difference is known as a datum shift. Depending on where you are in …The Insider Trading Activity of Reinhart Harald on Markets Insider. Indices Commodities Currencies StocksWGS84 is not an option in the conversion tool. If I have records from all over the world then which NAD 83 do I use in place of WGS84? For now, you may use HTDP to transform WGS84 to NAD 83 first and use the transformed NAD 83 coordinates in NCAT. Future versions of NCAT may support WGS84. You may access HTDP from here1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid whereas NAD83 (North American 1983 Datum) utilizes the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has a 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world whereas NAD83 is mostly used in the USA and Canada. 4.

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00:00 - What does WGS 84 mean?00:40 - Does Google Earth use WGS84?01:09 - What is the difference between Itrf and WGS84?01:47 - Why do we use WGS 84?Laura S.... NAD83; up to 2 meters for WGS84 vs. NAD83 9/1/2020 2-14 Geo327G/386G: GIS & GPS Applications in Earth Sciences Jackson School of Geosciences, University of Texas at Austin NAD27, NAD83 & WGS 84 Coordinates Datum Latitude Longitude NAD27 30.283678 -97.732654 NAD83 30.283658 -97.732548 WGS84 30.283658 -97.732548 9/1/2020 2-15 (Bellingham, WA) NAD 83 and NAVD 88, although still the official horizontal and vertical datums of the National Spatial Reference System (NSRS), have been identified as having shortcomings that are best addressed through defining new horizontal and vertical datums. Specifically: NAD 83 is non-geocentric by about 2.2 meters. NAVD 88 is both biased (by about one ...A pesar que hace algún tiempo los Institutos Geográficos en Latino américa oficializaron el cambio a wGS84 como proyección estandarizada, el cambio a nivel de uso va un tanto lento. En realidad la proyección es siempre cilíndrica y el cambio apenas implica un cambio de Datum entre NAD27 y NAD83, no obstante las implicaciones se vuelven ...The NAD 83 and the NAVD 88 are the recommended datums to use in USGS publication series information products. The use of these datums establishes a common reference for all horizontal and vertical data in the NSRS for the conterminous United States and Alaska. The NAD 83 and the NAVD 88 datums also provide the necessary linkages for Global ...

WGS84 (World Geodetic System 1984) ja NAD83 (North American Datum 1983) on mõlemad geodeetilised koordinaatsüsteemid, mida kasutatakse positsioonide määratlemiseks Maa pinnal. WGS84 on globaalne koordinaatide süsteem, mida kasutatakse laialdaselt GPS-is ja satelliidipõhises navigatsioonis. NAD83 on piirkondlik koordinaatide süsteem, mida kasutatakse Põhja-Ameerikas mõõdistamise ja ... NAD83; up to 2 meters for WGS84 vs. NAD83 9/1/2020 2-14 Geo327G/386G: GIS & GPS Applications in Earth Sciences Jackson School of Geosciences, University of Texas at Austin NAD27, NAD83 & WGS 84 Coordinates Datum Latitude Longitude NAD27 30.283678 -97.732654 NAD83 30.283658 -97.732548 WGS84 30.283658 -97.732548 9/1/2020 2-15 (Bellingham, WA) North American Datum of 1983’s (NAD83) relationship with the International Terrestrial Reference Frame (ITRF) and the World Geodetic System of 1984 (WGS84) …Apr 9, 2020 · 1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid whereas NAD83 (North American 1983 Datum) utilizes the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has a 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world whereas NAD83 is mostly used in the USA and Canada. 4. That’s why the U.S. National Geodetic Survey is now modernizing its National Spatial Reference System (NSRS). They will replace NAD83 as their national geometric reference system with the North American Terrestrial Reference Frame of 2022 (NATRF2022). This update was originally planned for 2022 but has been delayed until …Hazus input datasets, including state inventory data, were converted from NAD83 to the World Geodetic System 1984 (WGS84) coordinate system in order to better support U.S. territories and long-term goals for international hazard modeling.The sibling bond is a special one. I have three brothers and as I have gotten older I realize one of the greatest gifts my parents ever gave me was... Edit Your Post Published by M...The majority of the county layers were in WGS84 and automatically loaded into the correct extent/location, but some (such as King County) were in NAD83 (ESPG: 4269) is placed over West Africa in the OSM map. What do I need to do to get this King County layer to load in the correct place on OpenLayers map?

Understanding the Difference Between WGS84 and NAD83 As a Digital Nomad, I often come across various geodetic datums and coordinate systems. One common confusion that arises is the difference between WGS84 (World Geodetic System 1984) and NAD83 (North American Datum 1983). While they may seem similar, they …

Positions obtained using the North American Datums of 1927 (NAD 27) and 1983 (NAD 83) are based on different earth shapes--or ellipsoids--and used the best technology available at the time. Mathematically, NAD 83 is a stronger datum because all previously existing horizontal stations and newer GPS surveyed stations were adjusted simultaneously.WGS84 (World Geodetic System 1984) dan NAD83 (North American Datum 1983) keduanya adalah sistem koordinat geodetik yang digunakan untuk menentukan posisi di permukaan bumi. WGS84 adalah sistem koordinat global yang banyak digunakan dalam GPS dan navigasi berbasis satelit. NAD83 adalah sistem koordinat regional yang digunakan di Amerika Utara untuk keperluan survei dan pemetaan.1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid where as NAD83 (North American 1983 Datum) uses the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world where as NAD83 is mostly used in USA and Canada. 4.What is prompting all this change in the French capital? Interlopers from the East. Le Grand, a magnificent hotel in Paris overlooking the Opera house, has been sold to Qatari-back...What to watch for today What to watch for today At least part of Congress reaches a compromise. Senators from both parties are close to a deal to re-open the US government until Ja...realization of NAD83 fixed to the North American tectonic plate. 2. Problems At the time of its initial realization, NAD83 was intended to be a geocentric system and was compatible with the other geocentric systems of the time, such as the original realization of WGS84. However, due to the use of more accurate techniques, it is now known thatGet ratings and reviews for the top 10 foundation companies in Charlestown, IN. Helping you find the best foundation companies for the job. Expert Advice On Improving Your Home All...The North American Datum of 1983 (NAD83) is the most current datum in North America. It provides latitude and longitude and some height information using the reference ellipsoid GRS80. NAD83 corrects some of the distortions from NAD27 over distance by using a more dense set of positions from terrestrial and Doppler satellite data.North American Datum of 1983 (NAD83) replaced NAD27 and was adopted as the official datum for California and the United States. It is an earth-centered datum based on ground control points and ... WGS84 and NAD83 can be considered equivalent. For example, data collected in WGS84 can be treated as NAD83, unless you are trying to map locations moreAre you a Bad Elf Flex user switching between standard and extreme mode? If so, you’re probably collecting coordinates in differing datums and need a way to...

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Mar 30, 2024 · The primary distinction between these systems lies in the ellipsoid they use. NAD83 employs the Geodetic Reference System 80 (GRS80) ellipsoid, while WGS84 utilizes the WGS 84 ellipsoid. Although the dimensions of these ellipsoids differ slightly, they play a crucial role in accurately determining positions and coordinates on the Earth’s surface. NAD‑83, GRS‑80, and AGD‑66 are examples of local datums. GNSS observations and local coordinate systems. GNSS measurements are referenced to the 1984 World Geodetic System reference ellipsoid, known as WGS‑84. However, for most survey tasks, results in terms of WGS‑84 have little value. It is better to display and store results in ...As Andre says, set a custom CRS which will allow something with a CRS of lets say WGS84 be transfromed so it displays correctly on OSGB64. I was just about to post the same link as he has done to show alterations.Here you can convert the most common coordinates into the other formats. This works in all directions and with all valid values. The valid values for the respective system can be found by moving the mouse over the input examples. After entering the values to be converted, either click on the calculator or confirm with the Enter key.The old coordinates were not wrong, just different. Positions obtained using the North American Datums of 1927 (NAD 27) and 1983 (NAD 83) are based on different earth shapes--or ellipsoids--and used the best technology available at the time. Mathematically, NAD 83 is a stronger datum because all previously existing horizontal stations and …It is true that NAD83 is a horizontal datum, but the setup in the question uses EPSG:5498-- a compound coordinate reference system (CRS) that combines both NAD83 as a horizontal CRS and NAVD88 as a vertical CRS. However, this concern is valid when looking at the particular form of WGS84 being used -- EPSG:4326. Looking at the linked …As NAD83 has aged, there has been constant improvement in geodesy. When NAD83 was created, it was intended to be geocentric. It is known that the center of the reference ellipsoid of NAD83, GRS80, is about 2.24 meters from the true geocenter. However, there is a reference system that is geocentric. ... WGS84 and NAD83 ...WGS84 (World Geodetic System 1984) ja NAD83 (North American Datum 1983) on mõlemad geodeetilised koordinaatsüsteemid, mida kasutatakse positsioonide määratlemiseks Maa pinnal. WGS84 on globaalne koordinaatide süsteem, mida kasutatakse laialdaselt GPS-is ja satelliidipõhises navigatsioonis. NAD83 on piirkondlik … ….

1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid where as NAD83 (North American 1983 Datum) uses the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world where as NAD83 is mostly used in USA and Canada. 4.00:00 - What does WGS 84 mean?00:40 - Does Google Earth use WGS84?01:09 - What is the difference between Itrf and WGS84?01:47 - Why do we use WGS 84?Laura S....Cat allergies, like sexuality, run on a spectrum. If you’re only slightly allergic, you might be ready to bear it, if you can find a cat that will meet you halfway. While there’s n...What is a Datum? A datum defines how a coordinate system is seated over the ellipsoid. The origin of the new NAD83 system is the centre of mass of the Earth, whereas the old North American Datum 1927 (NAD27) had a different origin, making it useful only in North America. GPS receivers also use the centre of mass of the Earth as their …Fluid Overload is more fluid than the heart can effectively cope with. Fluid overload (hypervolemia) occurs when the circulating volume is excessive. Try our Symptom Checker Got an...WGS84 frames are specifically named NAD83 (CORS96) and WGS84 (G1150). Thus, when the receiver tell us that the computed coordinates using GPS observations are referred to the WGS84, they actually mean WGS84(G1150). On the other hand, if we use CORS coordinates data, or the OPUS service, the NAD83 reference frame to which theseMany mompreneurs want to start a business that provides flexibility, and that can be done from home, here are 14 best business ideas. Starting a Business | Tip List WRITTEN BY: Bla...Convertir en NAD83 convertit les coordonnées en système NAD83. Les coordonnées d'origine peuvent être dans le système: UTM, GPS / WGS84, NAD83 et d'autres systèmes populaires. En option, vous pouvez sélectionner le système en entrant le code EPSG. La base de données du registre EPSG comprend plus de 1000 entrées.4. The NAD 27 and the NAD 83 are different in their ellipsoids. 5. When talking about accuracy, it has been said that the North American Datum of 1983 is more accurate than the North American Datum of 1927. 6. The NAD 83 uses modern technology; the NDA 27 has been done only manually. Author. Nad83 vs wgs84, Understanding the Difference Between WGS84 and NAD83 As a Digital Nomad, I often come across various geodetic datums and coordinate systems. One common confusion that arises is the difference between WGS84 (World Geodetic System 1984) and NAD83 (North American Datum 1983). While they may seem similar, they …, Learn the 10 differences between WGS84 and NAD83, two coordinate systems used in GIS. Compare their ellipsoids, geoids, accuracy, coverage, and …, 1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid whereas NAD83 (North American 1983 Datum) utilizes the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has a 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world whereas NAD83 is mostly used in the USA and Canada. 4., Mar 30, 2024 · The primary distinction between these systems lies in the ellipsoid they use. NAD83 employs the Geodetic Reference System 80 (GRS80) ellipsoid, while WGS84 utilizes the WGS 84 ellipsoid. Although the dimensions of these ellipsoids differ slightly, they play a crucial role in accurately determining positions and coordinates on the Earth’s surface. , Are you a Bad Elf Flex user switching between standard and extreme mode? If so, you’re probably collecting coordinates in differing datums and need a way to..., NAD 83 is based on the Geodetic Reference System of 1980, which is a more modern and accurate system compared to the Ellipsoid used in NAD 27. 3. What was the survey point used for NAD 27? NAD 27 was computed with a single survey point, known as MEADES RANCH, located in Kansas. This point served as the datum point for the …, Developers are stepping in with open-source tools that allow anyone from academics to your everyday smartphone user to improve maps of the continent. In map after map after map, ma..., NADCON, an acronym for North American Datum Conversion, is a datum transformation program created by the U.S. National Geodetic Survey (NGS). It is suitable for the United States, Puerto Rico, and the Virgin Islands but only for conversion between the NAD27, NAD83, High Precision GPS Network (HPGN) readjustment of NAD83, and selected …, The Republic of Molossia is a little-known micronation in the Nevada desert, with its own currency, navy, space program, and flag. “Beyond this point, you are no longer in United S..., Convertir en NAD83 convertit les coordonnées en système NAD83. Les coordonnées d'origine peuvent être dans le système: UTM, GPS / WGS84, NAD83 et d'autres systèmes populaires. En option, vous pouvez sélectionner le système en entrant le code EPSG. La base de données du registre EPSG comprend plus de 1000 entrées., The original WGS 84 realization essentially agrees with NAD 83 (1986). It is generally assumed, and this assumption is substantiated by the National Geodetic Survey, that WGS 84 (original) is identical to NAD 83 (1986). In 1994, DoD introduced a realization of WGS 84 that was based completely on GPS observations., Mar 17, 2016 ... I noticed in the documentation for las2las that is can convert between projections as long as the source and target spatial reference use the ..., The original WGS 84 realization essentially agrees with NAD 83 (1986). It is generally assumed, and this assumption is substantiated by the National Geodetic Survey, that WGS 84 (original) is identical to NAD 83 (1986). In 1994, DoD introduced a realization of WGS 84 that was based completely on GPS observations. , Air Canada has some good deals to Beijing and Shanghai during the months of February and March 2020. Round-trip economy fares are as low as $350 per person. Update:Some offers ment..., Why did NGS change from NAD 27 to NAD 83? ... This paper contains a similarity transformation between WGS84 (730) and ITRF92. If one accounts for plate motion, the parameters are: dx -0.9 cm: dy : 0.8 cm: dz -2.3 cm: Rx -3.6 mas: Ry : 0.6 mas: Rz : 3.1 mas: scale -7.7 ppBillion: That paper has further references that address the formulation …, Most GPS are set to WGS84 out-of-the-box (same as NAD83). You convert between datum using NADCON transformation Æ do this in ArcGIS! X VERTICAL DATUM SHIFT • Sea level for an area is measured over a period of time. This is called a tidal epic. • Sea level is rising • These tidal epics are used to develop the vertical datum for an area, Positions obtained using the North American Datums of 1927 (NAD 27) and 1983 (NAD 83) are based on different earth shapes--or ellipsoids--and used the best technology available at the time. Mathematically, NAD 83 is a stronger datum because all previously existing horizontal stations and newer GPS surveyed stations were adjusted simultaneously., The World Geodetic System of 1984 (WGS84) is identical to NAD83 for most practical purposes within the United States. WGS84 is the default datum setting for almost all …, The World Geodetic System ( WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM). , WGS84. NAD83. Definice. WGS84 z roku 1984 je datum, které zahrnuje uspořádání, která se mění s časem. NAD83 z roku 1983 je sudý a kontrolní údaj pro Spojené státy, Střední Ameriku, Mexiko a Kanadu NAD83 byl dodán v roce 1986. Zkratka. Zkratka pro WGS84 je The World Geodetic System. Zkratka pro NAD83 je North American Datum., , 1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid whereas NAD83 (North American 1983 Datum) utilizes the Geodetic Reference System (GRS80) ellipsoid. 2. WGS84 has a 0.21mm longer ellipsoid than NAD83. 3. WGS84 is used all over the world whereas NAD83 is mostly used in the USA and Canada. 4., NAD83 shaped ellipsoid centered at the ITRF origin to derive ITRF00 ellipsoid heights. Ellipsoid heights NAD83 vs. ITRF00 - Defined origins are best estimate of the center of mass; NAD83 is not geocentric. Move origin; move ellipsoid surface as indicated by scale shown on map. Ellipsoid height differences reflect the non-geocentricity of NAD83., For example, the latitude and longitude location in a NAD27 datum differs from that same benchmark in NAD83 or WGS84. This difference is known as a datum shift. Depending on where you are in North America, NAD27 and NAD83 may differ in tens of meters for horizontal accuracy., Medicine Matters Sharing successes, challenges and daily happenings in the Department of Medicine ARTICLE: Estimation of the Global Gap in Clinic Visits for Hypertension Care Betwe..., The apparent investigative stillness around Ivanka is a potent reminder that the probes into Donald Trump's actions are as much about image as they are about the law. Ivanka Trump ..., For applications with an accuracy of better than 1m, replaced by NAD83(HARN) / Conus Albers (CRS code 5071). Data analysis and small scale data presentation for contiguous lower 48 states. powered by MapTiler. Search Map Transform API Pricing About. L. Search Map ... WGS84 bounds:-172.54 23.81, Bumetanide: learn about side effects, dosage, special precautions, and more on MedlinePlus Bumetanide is a strong diuretic ('water pill') and may cause dehydration and electrolyte ..., WGS84 is standard for GPS. The Global Positioning System uses the World Geodetic System (WGS84) as its reference coordinate system. It consists of a reference ellipsoid, a standard coordinate system, altitude data, and a geoid. Similar to the North American Datum of 1983 (NAD83), it uses the Earth’s center mass as the coordinate origin., The original WGS 84 realization essentially agrees with NAD 83 (1986). It is generally assumed, and this assumption is substantiated by the National Geodetic Survey, that WGS 84 (original) is identical to NAD 83 (1986). In 1994, DoD introduced a realization of WGS 84 that was based completely on GPS observations., Hazus input datasets, including state inventory data, were converted from NAD83 to the World Geodetic System 1984 (WGS84) coordinate system in order to better support U.S. territories and long-term goals for international hazard modeling., The GPS data is post-processed with Trimble Pathfinder office and exported as shapefiles into the local state plane coordinate system. The shapefiles are then imported into our SDE which is in WGS84 using the WGS_1984_ (ITRF00)_To_NAD_1983 Datum transformation. When comparing data exported from PostGIS to the data in our SDE …, NAD27 vs. NAD83. NAD27 is based on the Clarke Ellipsoid of 1866, whereas NAD83 is based on the GRS 80 ellipsoid. The Clarke Ellipsoid is much less accurate. A point with a given latitude and longitude in NAD27 may be many tens of meters from another point having the identical latitude and longitude in NAD83.