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題 名 | 一維球面快速傅利葉轉換法計算臺灣地區大地起伏之研究=The Computation of Geoid Undulations for Taiwan by the 1D-FFT Method |
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作 者 | 崔國強; 柏茂青; | 書刊名 | 測量工程 |
卷 期 | 39:3 1997.09[民86.09] |
頁 次 | 頁19-33 |
分類號 | 440.9 |
關鍵詞 | 快速傅利葉轉換法; 數值地形模型; 地形效應; 先減後加技術; FFT method; Digital terrain model; Terrain effect; Remove-restore technique; |
語 文 | 中文(Chinese) |
中文摘要 | 隨著GPS高精度定位技術快速發展,因此一高精度之大地起伏亦隨之迫切需要,以 便將 GPS 測得之橢球高轉為正高。 本文計算臺灣地區一新的高解析大地水準面其涵蓋區域 介於北緯 21.55 °至 25.5 °,東經 119.5 °至 122.45 °之範圍。本文採用一維球面快 速傅利葉轉換法,依先減後加技術, 結合 EGM96 全球重力位模式、臺灣地區 3' × 3' 平 均重力異常的網格資料和數值地形資料,以海勒默特第二壓縮理論考慮地形效應,嚴密計算 臺灣地區大地起伏。 文中亦分別比較以二維平面、球面及一維球面快速傅利葉轉換法,計算臺灣地區大地水準面 結果之差異;並針對全球重力位模式 EGM 96 在臺灣地區重力場量之密合性及適用性做一探 討,而地形質量效應對精密計算大地水準面之影響量,亦為研究重點。由計算結果顯示以一 維球面快速傅利葉轉換法並考慮地形質量效應之影響所求得臺灣地區大地起伏與 GPS 結合 水準測量算得之幾何法大地起伏比較,其差值之均方根值為 8 公分。 |
英文摘要 | With the rapid expansion applications of GPS positioning and the improvement of positioning accuracy. there is a demanding need for an unified gravimetric geoid of high accuracy. It can be used together with the GPS-derived heights to provide orthometric heights. A new, high-resolution and high-precision geoid has been computed for the Taiwan area, ranging from 21.55 ° N to 25.5 ° N in latitude and 119.5 ° E to 122.45 ° E in longitude. The computations was carried out by using EGM 96 geopotential model, 3' × 3' mean gravity anomaly grid and digital terrain model. The remove-restore technique was adopted for the computation of terrain effect by Helmert's condensation reduction. The contribution of the local gravity data to the geoid was computed strictly by the 1D-FFT technique, which allows for the evaluation of the discrete spherical Stokes' integral without any approximation. In this study, we compared the difference of the geoid undulations computed by 2D planer FFT, 2D spherical FFT and 1D spherical FFT method. We also tested the adaptability of using EGM96 to calculate the gravitational quantities in the region of Taiwan. The terrain effects on the geoid computation were also studied. The comparison of the gravimetric geoid with GPS/leveling-derived undulations shows the RMS is less than 10cm. |
本系統中英文摘要資訊取自各篇刊載內容。