GPS-WGS 84 koordinatlarının 2 ve 3 boyutlu transformasyonlarında ölçek faktörünün etkisi ve düşey transformasyon yöntemleri
effects of scale factor on GPS-WGS 84 coordinate transformations in 2-d & 3-d and methods for vertical transformations the navstar gps
- Tez No: 66761
- Danışmanlar: DOÇ. DR. MUHAMMED ŞAHİN
- Tez Türü: Yüksek Lisans
- Konular: Jeodezi ve Fotogrametri, Geodesy and Photogrammetry
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1997
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Jeodezi ve Fotogrametri Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 139
Özet
ÖZET Global Positioning System (GPS), uydulardan aldığı sinyallerle herhangi bir yerde ve zamanda yüksek doğrulukta konum, hız ve zaman belirleyen bir sistemdir. GPS, jeodezik ve fotogrametrik ölçmelerde karşılaşılan bir çok sorunu ortadan kaldırmakta, noktalar arası görüş zorunluluğunun olmaması, sınırsız sayıda kullanıma olanak vermesi ve ekonomik olması nedeniyle klasik ölçme tekniklerinin yerini almaktadır. GPS sisteminin 24 uyduya tamamlanarak daha iyi bir geometrik dağılım sağlanması, ölçme ve hesaplama tekniklerindeki gelişme sayesinde GPS, haritacılık sektörünün dışında da kullanılmaya başlanmıştır. Uydulardan alınan tüm bilgiler GPS sistemi için geliştirilmiş WGS 84 (World Geodetic System 1984) referans elipsoidi üzerindedir. WGS 84 yersel üç boyutlu koordinat sistemidir. Uygulamada yer noktalannın koordinatları global bir şekil üzerinde hesaplanmayıp, jeodezik dik koordinatlar ve düzlem koordinatlar olarak lokal koordinat sisteminde hesaplanırlar. GPS ile ölçüm sonucu elde edilen WGS 84 koordinatlarının pratikte kullanılabilmesi için kullanılan jeodezik koordinat sistemine dönüşümü yapılması gereklidir. Benzerlik dönüşümü, belirli bir tipteki koordinat sistemini, aynı yapıdaki başka bir koordinat sistemine dönüştürür. Her iki koordinat sisteminde koordinatları bilinen noktalar yardımı ile dönüşüm parametreleri (dönmeler, ötelemeler ve ölçek faktörü) hesaplanır. Üç boyutlu, iki boyutlu ve bir boyutlu benzerlik dönüşümleri vardır. Bu çalışmada, dönüşüm parametrelerinden ölçek faktörünün üç boyutlu ve iki boyutlu benzerlik dönüşümü sonuçlarına etkisi gösterilmektedir.“”GPS ile elde edilen yükseklikler (elipsoidal yükseklik) geometrik anlama sahiptir, güncel mühendislik uygulamalannda ise yerel yükseklik sistemleri (ortometrik yükseklik) kullanılmaktadır. Bu nedenle GPS yüksekliklerinin kullanılan yerel sisteme dönüştürülmesi gerekmektedir. Bu çalışmada GPS ölçmelerinden elde edilen elipsoidal yükseklikler her iki sistemde de yükseklikleri bilinen noktalar yardımıyla, üç ayn enterpolasyon yöntemiyle yerel yükseklik sistemine dönüştürülmüştür ve enterpolasyon sonucu çıkan farklar, ölçmelerden elde edilen farklarla karşılaştırılmıştır.
Özet (Çeviri)
SUMMARY (Navigation System with Time and Ranging Global Positioning System ) is a satellite-based radio navigation system providing precise three-dimensional position, navigation, and time information to the users. The system will be continuously available on a world-wide basis, and is independant of meteorological conditions. Now the system consists of 24 satellites, placed in orbits of about 20183 km altitude above the earth' s surface. The final arrangement of satellites is planed in such a way that at least four satellites are simultaneously visible above the horizon anywhere on the earth in 24 hours a day. The GPS system is explained by means of three segment:. Space Segment. Control Segment. User Segment The space segment consist of 24 satellites and these satellites are placed in almost circular orbits in six orbital planes with an orbital inclination of 55 degrees. The otbital height is about 20183 km. GPS satellites transmit L1 (1575.42 MHz) and L2 (1227.60 MHz) band signals for positioning aplications. The satellites use the C/A code (1.023 MHz) which is modulated on the L1 and the P code (10.23 Mhz) which is modulated on both the L1 and L2 for transmitting these signals. The tasks of the control segment are to. monitor and control the satellite system continously. determine the GPS system time. predict the satellite ephemerides and the behavior of the satellite clocks update periodicaly the navigation message for each particular satellite. The control segment for GPS consists of one master control station, five monitor stations and three ground antennas. The monitor stations receive all satellite signals from the visible satellites, and then the master control station collects the data from the monitor stations and precomputes satellite ephemerides and the behavior of the satellite clocks and formulates thenavigation data. The massage data are transmitted to the ground antennas and uplinked via S-band to the satellite in view. The user segment consist of several types of receivers on the earth which are collecting the signals in order to derive their locations, velocity etc. Various techniques have been developed in recent years that exploit the capability of GPS to provide precise coordinates after a very short observation time, or even while the receiver is moving along a trajectory. The rationale behind the subdivision of GPS surveying is whether the receiver is taking measurements while it is in motion, and the coordinates of the trajectory can be determined (kinematic mode), or whether the receiver is switched off during transportation, and coordinates can only be determined when the antenna is stationary (static mode). The reference frame of GPS is the World Geodetic System 1984 (WGS 84). The origin of the WGS 84 Coordinate System is the center of mass of the earth; the WGS 84 Z - axis is parallel to the direction of the Conventional Terrestrial Pole (CTP) for polar motion, the X -axis is the intersection of the WGS 84 reference meridian plane and the plane of the CTP' s equator, the reference meridian being parallel to the Zero Meridian and the Y- axis completes a right - handed, earth fixed orthogonal coordinate system measured inthe plane of the above equator, 90° east of the X - axis. WGS 84 Zero Meridian Earth's Center o Mass WGS Figure 1 : WGS 84 reference frame When using GPS, the coordinates of terrestrial sites are obtained in WGS84 reference frame. However, the surveyor is not, usually, interested in computing the coordinates of the terrestrial points in a global frame, rather, the results are preferred in a local coordinate frame. Because of the WGS 84 is a geocentric system and the local system is not, certain transformations are required. Similarity transformation is one of thetransformation methods to transform geocentric WGS 84 coordinates to local terrestrial coordinates. A transformation in which the scale factor is the same in all direction called similarity transformation. A similarity transformation preserves shape, so angles will not change, but the lengths of lines and the position of points may change. A similarity transformation transforms one coordinate system from a certain type to another coordinate system of the same type and can be done in three-dimension, two-dimension and one-dimension. Figure 2: Three-dimentional similarity transformation The mathematical model of the three-dimensional similarity transformation is: (1) X, Y, Z : Local reference system x, y, z : WGS84 reference system X0, Y0, Z0 : shifts between two system k : scale factor Rx, Ry, Rz : rotationsFigure 3: Two-dimentional similarity transformation The mathematical model of the two-dimensional similarity transformation is: cos# -sin0 (2) X, Y : Local reference system x, y : WGS84 reference system X0, Y0: shifts between two system k : scale factor & : rotation In this study, the effection of the scale factor on the transformation results is searched in both dimension. In three-dimentional similarity transformation to see this effect on the transformation results, the scale factor is devided into its components as kx, ky, k* And the number of the parameters increase from 7 to 9. The mathematical model of the 9 parameter transformation is: X Y Z + 1 (3)In two-dimentional similarity transformation to see this effect on the transformation results, we devide the scale factor into its components as kx, ky. And the number of the parameters increase from 4 to 5. The mathematical model of the 5 parameter transformation is: cos0 -sin0 sin0 cos0 \kyy_ kx (4) We compare the results of 7 parameter transformation and 9 parameter transformation results both in Cartesian coordinates system and plane coordinate system and the results of 4 parameter and 5 parameter transformation results in two-dimensional transformation. GPS can provide horizontal control more accurate than convensional methods. Additionally, the GPS system can provide this level of precision without requiring the intervisibility of the stations. One drawback is that the GPS does not provide elevations above main sea level. GPS heights are referenced to WGS 84 ellipsoid. But surveyors and engineers are in most cases interested in the ortometric height as measured above some datum reference surface, identified as geoid. Geoid: The geoid is one of a whole family of equipotential, or level surfaces of the earth's gravity field. Ellipsoid: A simple mathematical surface which best approximates the shape of the earth. In relation to the surfaces described above, there are three height values that may be calculated for a single point on the earth. They are: 1. Geoid (Height) Undulation (N) - The distance between the surface of the geoid and the surface of the ellipsoid. 2. Ellipsoid Height (h) - The distance between the surface of the ellipsoid and the surface of the earth. 3. Ortometric Height (H) - The distance from the surface the geoid to the surface of the earth, when measured along the plumb line. In most cases the ortometric height is also considered the mean sea level elevation of the point. The relationship between these three heights are shown graphically in Figure 4 and are related by the following equation: H = h-N (5) xinPlumbline ellipsoid normal TERRAIN -_ ro rallel to geoid ANTO parallel to ellipsoid Figure 4: The GPS heighting problem From the basic data obtained from the GPS system and with the help of statistical adjustment programs, the GPS user can obtain the location of each new station and its ellipsoid height. The only term that is still missing in Equation (5) is the geoid undulation. If the geoid undulation can be calculate accurately, the final term in Equation (5) will be known and the ortometric height for any point can be determined. For many places arround the world, however, not enough gravity data are available for the computation of a sufficiently detailed geoid. Geoid undulations obtained using interpolative techniques. In this study, three different interpolation techniques is used to obtain the geoid undulation. These are:. Polynomial Method. Weighted- Average Method. Multiquadrics Method Geoid undulation are computed based on the control points that have both elevations and elipsoid heights. With the help of different number of control points, the geoid undulations are determined. At the end of the interpolation with three methods, the geoid undulations derived from the interpolation are compared with these derived directly by differencing GPS and geometric levelling. XIV
Benzer Tezler
- Yersel ve GPS ölçülerinin 3 boyutlu geometrik modelle dengelenmesi
Başlık çevirisi yok
ALİ TÜRKEZER
Yüksek Lisans
Türkçe
1998
Jeodezi ve Fotogrametriİstanbul Teknik ÜniversitesiJeodezi ve Coğrafi Bilgi Sistemleri Ana Bilim Dalı
DOÇ. DR. ERSAY ARSLAN
- Uydu tekniklerinin ağ sıklaştırmasında kullanılabilirliği üzerine bir araştırma
Başlık çevirisi yok
MUSTAFA ŞİMŞEK
Doktora
Türkçe
1995
Jeodezi ve FotogrametriYıldız Teknik ÜniversitesiJeodezi ve Fotogrametri Ana Bilim Dalı
PROF. DR. HÜSEYİN DEMİREL
- İstanbul nirengi çalışmalarının yersel ve GPS ölçüleri ile değerlendirilmesi ve analizi
Başlık çevirisi yok
NİHAT ERSOY
Doktora
Türkçe
1997
Jeodezi ve FotogrametriYıldız Teknik ÜniversitesiJeodezi ve Fotogrametri Ana Bilim Dalı
PROF. DR. HASAN KIRAN
- Bir test ağında ortometrik yükseklikler ile elipsoidal yüksekliklerin karşılaştırılması
Comparison of the ellipsoidal heights and orthometric heights in a test network
ATALAY OKAN ERDOĞAN
- GPS verilerinin işlenmesi ve elipsoidal koordinatların ülke sistemine dönüştürülmesi
Processing of GPS observations and transforming ellipsoidal coordinates into the national system
İSMAİL ŞANLIOĞLU
Yüksek Lisans
Türkçe
1998
Jeodezi ve FotogrametriSelçuk ÜniversitesiJeodezi ve Fotogrametri Ana Bilim Dalı
DOÇ.DR. CEVAT İNAL