擷取Raster對象的RPC（Rational Polynomial Coefficients）相關資訊。如果Raster對象具備RPC資訊，則返回一個JSON格式的字串；如果不具備RPC資訊，則返回NULL。
文法
text ST_RPCGeoreference(raster raster_obj)參數
| 參數名稱 | 描述 |
| raster_obj | Raster對象。 |
描述
ST_RPCGeoreference函數返回的RPC參數是基於JSON格式的字串，描述了RPC空間的參考資訊。支援的參數如下：
| 參數名稱 | 描述 | 類型 |
| lineOff | 線位移 | float |
| sampOff | 採樣位移 | float |
| latOff | 緯度位移 | float |
| longOff | 經度位移 | float |
| heightOff | 高程位移 | float |
| lineScale | 線比例 | float |
| sampScale | 採樣比例 | float |
| latScale | 緯度比例 | float |
| longScale | 經度比例 | float |
| heightScale | 高程比例 | float |
| lineDenCoeff | 線分母係數（20個） | float array |
| lineNumCoeff | 線分子係數（20個） | float array |
| sampNumCoeff | 採樣分子係數（20個） | float array |
| sampDenCoeff | 採樣分母係數（20個） | float array |
| errBias | 錯誤誤差。以米為單位的映像中所有點的水平軸的均方根偏差誤差，未知時為-1.0。 | float |
| errRandom | 隨機誤差。以米為單位的映像中每個點每水平軸的均方根隨機誤差，未知時為-1.0。 | float |
樣本
SELECT ST_RPCGeoreference(raster_obj) FROM raster_table where id=1;
__________________________________
{"lineOff":12800.0,"sampOff":4008.0,"latOff":55.0203,"longOff":27.0478,"heightOff":179.0,"lineScale":12800.0,"sampScale":4008.0,"latScale":0.1238,"longScale":0.0685,"heightScale":300.0,"errBias":-1.0,"errRandom":-1.0,"lineDenCoeff":[1.0,-0.00050066513,-0.0014578309,0.0006037474.
.4,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0],"lineNumCoeff":[-0.002104832,-0.01642616,-1.027459,0.0041820025,-0.0019027952,0.000016143133,0.00047863558,-0.00021278669,0.0069588307,-0.0000022605722,-2.2259552e-7,-3.7469372e-7,0.00046486457,-1.8012888e-8,0.0.
.000051407583,0.00075661479,-5.4524409e-7,1.3940799e-7,-0.000018281596,2.4215581e-9],"sampDenCoeff":[1.0,-0.00050066513,-0.0014578309,0.00060374744,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0],"sampNumCoeff":[1.0,-0.00050066513,-0.0014578309,0.00060374744,0.0.
.,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0]}