GEOS庫 介紹 （轉）

http://wiki.woodpecker.org.cn/moin/lilin/geos-introduce

介紹

GEOS是一個集合形狀的拓撲關系操作實用庫（可能這么說不太准確），簡單得說，就是判斷兩個幾何形狀之間關系和對兩個幾何形狀進行操作以形成新的幾何形狀的庫。

其實學geos的好地方不是在GEOS的主站。而是在另一個地方，JTS Topology Suite (JTS)！

事實上，GEOS是仿照JTS做的。它其實是JTS的C++實現。

這里有幾份文檔，一份是開發者指南，一份是JTS技術說明書

GEOS主要支持幾種操作和計算：

空間關系計算，主要支持幾種計算

 

另外還支持多邊形化，連接有向線段，壓出節點等等操作。

 

geos for python的安裝

 

windows下的安裝

 

純粹的GEOS安裝

純粹的GEOS在windows下的安裝挺復雜,因為geos本來是為unix類系統寫得.作者好像在windows下花的時間不是很多.所以代碼很多在windows下都會出錯.不過我還是把它安裝上了.

1. 下載geos的geos-2.1.4版(更高的版本我沒有試過)解壓,假設解壓路徑下面都表示為$GEOSHOME
2. 進入$GEOSHOME\source\headers\geos,把platform.h.vc改名為platform.h,把version.h.in改名為version.h
3. 進入$GEOSHOME\source
4. 登記vcvars32.bat,如"D:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\vcvars32.bat",依你的vs安裝路徑和版本自己看着辦.

5. 運行nmake /f makefile.vc,注意,不要去$GEOSHOME\VisualStudio下開vc工程,那個工程如果沒有經過修改是不會運行成功的.nmake運行成功后,就有了geos.lib了,很好,現在geos的C++版已經可以用了.

6. 下面進入$GEOSHOME\swig\python目錄
7. 運行swig -c++ -python -modern -o geos_wrap.cxx ../geos.i (注意,這里的前提是你有swig,沒有去下一個swig for windows,然后把swig.exe所在目錄加入path環境變量
8. 打開setup.py,去掉有stdc++.lib的那行,然后把libgeos.a改成geos.lib
9. 運行python setup.py build
10. 運行python setup.py install

ok,成了!

 

讓geos作為ogr的輔助支持

上面的編譯方法實在有些……，不過有一種簡單的辦法也可以用到geos的功能，就是讓ogr添加geos支持。這種方法比較穩妥，也比較容易成功。

先參考上面的步驟編譯出geos.lib靜態庫。

然后打開gdal主目錄下的nmake.opt修改：

GEOS_CFLAGS = -IE:/clibs/geos-2.1.4/source/headers -DHAVE_GEOS
GEOS_LIB = E:/clibs/geos-2.1.4/source/geos.lib

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這兩行，把前面的“#”號去掉，然后把兩個路徑修改成geos下對應的目錄。注意：第一個需要修改的是從-I開始到-D結束，寫得是GEOS頭文件所在的headers目錄，而且-D前面有空格。第二個是從=開始，到行末，寫的是geos.lib所處路徑

然后重新編譯gdal庫。然后 nmake /f makefile.vc install安裝后就可以用GEOS支持了。

其實geos支持本來就應該在編譯gdal時直接添加了。到后面再加就有點浪費感情了。:-)

 

測試安裝是否成功

做個例子試一下,看是否添加成功：

>>> import ogr
>>> wkt = "POINT (1 1)" >>> geom = ogr.CreateGeometryFromWkt(wkt) >>> buf = geom.Buffer(1) >>> buf.ExportToWkt() 'POLYGON ((2 1,1.998629534754652 0.947664043758551,1.994521895368586 0.895471536 735323,1.98768834059584 0.843565534964204,1.97814760073505 0.792088309188096,1.9 65925826291005 0.741180954904707,1.951056516297928 0.690983005633592,1.933580426 500956 0.64163205046448,1.913545457647471 0.593263356935137,1.891006524194483 0. 546009500272454,1.866025403791921 0.500000000012961,1.83867056795439 0.455360964 998779,1.809016994385503 0.412214747722056,1.777145961469214 0.370679608965282,1 .743144825491414 0.330869393656712,1.707106781202421 0.292893218829326,1.6691306 06376652 0.256855174538628,1.629320391069609 0.22285403855904,1.587785252314266 0.190983005640886,1.544639035038874 0.161329432070062,1.500000000025921 0.133974 596230527,1.453990499767549 0.1089934758259,1.406736643105877 0.08645454237079,1 .358367949577434 0.066419573515133,1.309016994409106 0.048943483715945,1.2588190 45138659 0.034074173720615,1.207911690855819 0.021852399274284,1.15643446508014 0.012311659411183,1.104528463309327 0.005478104636107,1.052335956286284 0.001370 465247698,1.000000000044896 0.0,0.947664043803385 0.001370465242998,0.8954715367 79973 0.005478104626721,0.843565535008546 0.012311659397137,0.792088309232011 0. 021852399255615,0.741180954948073 0.034074173697375,0.69098300567629 0.048943483 688198,0.641632050506393 0.066419573482955,0.593263356976151 0.086454542334269,0 .546009500312456 0.108993475785135,0.500000000051841 0.133974596185631,0.4553609 65036432 0.161329432021158,0.412214747758377 0.190983005588108,0.370679609000173  0.222854038502531,0.330869393690077 0.256855174478545,0.292893218861073 0.29289 3218765832,0.25685517456867 0.330869393589983,0.222854038587295 0.37067960889549 9,0.190983005667276 0.412214747649411,0.161329432094515 0.455360964923472,0.1339 74596252976 0.499999999935197,0.108993475846283 0.546009500192447,0.086454542389 052 0.593263356853106,0.066419573531224 0.641632050380649,0.04894348372982 0.690 983005548192,0.034074173732236 0.741180954817972,0.021852399283619 0.79208830910 0263,0.012311659418207 0.843565534875514,0.0054781046408 0.89547153664602,0.0013 70465250047 0.947664043668878,0.0 0.999999999910204,0.001370465240648 1.05233595 6151776,0.005478104622028 1.104528463175373,0.012311659390113 1.156434464947106, 0.02185239924628 1.20791169072407,0.034074173685754 1.258819045008556,0.04894348 3674323 1.309016994281006,0.066419573466864 1.358367949451687,0.086454542316006 1.406736642982829,0.10899347576475 1.453990499647536,0.13397459616318 1.49999999 9909273,0.161329431996703 1.54463903492591,0.190983005561715 1.587785252205296,0 .222854038474274 1.629320390964932,0.256855174448499 1.669130606276555,0.2928932 18734082 1.707106781107177,0.330869393556614 1.743144825401285,0.370679608860604  1.777145961384448,0.412214747613085 1.809016994306332,0.455360964885815 1.83867 056788103,0.499999999896312 1.866025403724574,0.546009500152441 1.89100652413333 3,0.593263356812088 1.913545457592686,0.641632050338733 1.933580426452686,0.6909 83005505492 1.951056516256306,0.741180954774604 1.965925826256144,0.792088309056 347 1.978147600707046,0.843565534831169 1.98768834057477,0.895471536601369 1.994 521895354507,0.947664043624043 1.998629534747603,0.999999999865308 2.0,1.0523359 56106943 1.998629534761701,1.104528463130724 1.994521895382665,1.156434464902764  1.98768834061691,1.207911690680157 1.978147600763054,1.258819044965192 1.965925 826325865,1.30901699423831 1.95105651633955,1.358367949409777 1.933580426549225, 1.406736642941818 1.913545457702254,1.453990499607537 1.89100652425563,1.4999999 99870396 1.866025403859266,1.544639034888262 1.838670568027747,1.587785252168979  1.809016994464671,1.629320390930046 1.777145961553976,1.669130606243195 1.74314 4825581537,1.707106781075436 1.70710678129766,1.743144825371249 1.66913060647674 5,1.777145961356199 1.629320391174281,1.809016994279947 1.58778525242323,1.83867 0567856582 1.544639035151832,1.86602540370213 1.500000000142563,1.89100652411295 4 1.453990499887555,1.913545457574428 1.406736643228919,1.933580426436599 1.3583 67949703174,1.951056516242435 1.3090169945372,1.965925826244526 1.25881904526875 5,1.978147600697713 1.207911690987561,1.987688340567748 1.156434465213167,1.9945 21895349815 1.104528463443274,1.998629534745254 1.052335956420784,2 1))' >>>

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好大的一個緩沖區！不過這個多邊形的圓也太惡心了吧！

 

Linux下的安裝

這還要我說嗎？

 

./configure
make make install

 

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自己去折騰吧！

要OGR支持，只要在GDAL編譯的時候加入GEOS的編譯開關（似乎只要在編譯gdal前編譯安裝好GEOS，在configure GDAL的時候就會自動加入GEOS支持，當然各個系統不一定）重新編譯GDAL就可以了。

不懂編譯開關的設置？那就用./configure --help看看吧！一大堆？慢慢看。一堆英文看不懂？不是吧，我四級沒過都看懂了。實在看不懂？那么你就apt yum urpmi 什么的搞個二進制包吧！

祝你好運！