Venkat,I have completed the planned Shapefile quadtree mechanism.  The additionsto the traditional Shapelib are found in shptree.c (functions supportingquad tree searching and query).  There are also some new prototypes forthe tree stuff in shapefil.h ... including some prototypes for functionsyou don't require and hence that I haven't implemented at this time. I have also prepared a demonstration program using the API.  That isthe ``shpdumptree'' program, with the source code in shpdumptree.c.  Theshpdumptree program has two functions.  One is to dump an ASCII renderingof the internal quadtree, and the other is example use of a quad treesearching function. Dumping the Tree----------------The tree dumping is done as shown below.  The "-maxdepth" commandlineswitch can be used to control the maximum depth, otherwise it internallycomputes a ``reasonable depth'' to use based on the number of structuresin the shapefile.warmerda@gdal[207]% shptreedump -maxdepth 6 eg_data/polygon.shp( SHPTreeNode  Min = (471127.19,4751545.00)  Max = (489292.31,4765610.50)  Shapes(0):   ( SHPTreeNode    Min = (471127.19,4751545.00)    Max = (481118.01,4765610.50)    Shapes(0):     ( SHPTreeNode      Min = (471127.19,4751545.00)      Max = (481118.01,4759281.03)      Shapes(0):       ( SHPTreeNode        Min = (471127.19,4751545.00)        Max = (476622.14,4759281.03)        Shapes(0):         ( SHPTreeNode          Min = (471127.19,4751545.00)          Max = (476622.14,4755799.81)          Shapes(0):           ( SHPTreeNode            Min = (471127.19,4751545.00)            Max = (474149.41,4755799.81)            Shapes(6): 395 397 402 404 405 422           )          ( SHPTreeNode            Min = (473599.92,4751545.00)            Max = (476622.14,4755799.81)            Shapes(10): 392 394 403 413 414 417 426 433 434 447           )        )...A structure like the following represents one node in the tree.  Inthis case it cover the region of 473599.92 < X < 476622.14,and 4751545.0 < Y < 4755799.81.  There are ten shapes within this regionwho's shapeids are 392, 394 ... 447.  This node has no children nodes.          ( SHPTreeNode            Min = (473599.92,4751545.00)            Max = (476622.14,4755799.81)            Shapes(10): 392 394 403 413 414 417 426 433 434 447           )The heirarchy of indentation is intended to show the parent, child relationship between nodes, with the tree being deeper the further to theright you go. The `-v' flag to the program can be used to expand the report to includethe full information about shapes, not just their shapeid.  This can resultin a report looking more like this:          ...          ( SHPTreeNode            Min = (478095.78,4751545.00)            Max = (481118.01,4755799.81)            Shapes(3):            ( Shape              ShapeId = 448              Min = (479988.09,4753300.00)              Max = (480705.59,4754236.50)              Vertex[0] = (480136.59,4754174.50)              Vertex[1] = (480229.97,4754182.00)              Vertex[2] = (480370.09,4754200.50)              Vertex[3] = (480695.12,4754236.50)              Vertex[4] = (480687.97,4754129.50)              Vertex[5] = (480650.47,4754075.50)              Vertex[6] = (480520.62,4753948.00)              Vertex[7] = (480490.00,4753900.00)              Vertex[8] = (480499.78,4753840.50)              Vertex[9] = (480500.97,4753820.50)              Vertex[10] = (480534.75,4753660.50)              Vertex[11] = (480560.00,4753565.00)              Vertex[12] = (480574.91,4753550.50)          ...While it is possible to part the output of the shptreedump program, andinsert it into your database, my intention was that the shptreedump programwould serve as an example of how to pre-order traversal of the quad tree,and collect the information you will need to insert into your database. I would then expect you to write a new program based on shptreedump thatcalls a C API for your database to insert objects instead of printing themout.  Alternatively there may be an ASCII format for loading tables thatyou could modify the program to output. Searching---------The other thing that you can do with the shptreedump program is to perform a search on the quadtree.  For instance the following showssearching on a small region.% shptreedump -search 471127 4751545 476622 4759281 eg_data/polygon.shpShape 17: not in area of interest, but fetched.Shape 31: not in area of interest, but fetched.Shape 52: not in area of interest, but fetched.Shape 76: not in area of interest, but fetched.Shape 82: not in area of interest, but fetched.Shape 104: not in area of interest, but fetched.Shape 124: not in area of interest, but fetched.Shape 134: not in area of interest, but fetched.Shape 139: not in area of interest, but fetched.Shape 154: not in area of interest, but fetched.Shape 175: not in area of interest, but fetched.Shape 177: not in area of interest, but fetched.Shape 185: not in area of interest, but fetched.Shape 192: not in area of interest, but fetched.Shape 196: appears to be in area of interest.....I have included this capability (and the SHPTreeFindLikelyShapes() function)so that you can see a working example of how to search this quad tree. Note that searching is a multi-stage affair.  First a pass is made over the quadtree, collecting the shapeids of allshapes contained in a quadtree node for which the bounding rectangle overlapsthe search rectangle.  This is all accomplished by SHPTreeFindLikelyShapes()in shptree.c. The second phase is to fetch the actual shapes, and verify if their boundingbox falls within the area of interest.  This is necessary because the shape will tend to have a significantly smaller bounding rectangle than the tree node in which it is found.  This can result ``false positives'' on the firstphase search, as indicated by teh ``not in area of interest, but fetched''messages above.  This stage is done in the SHPTreeNodeSearchAndDump()function in shptreedump.c. A possible third phase is to verify that the actualy line segments in theshape actually cross the area of interest.  I don't both with this as itis complicated, and assuming that the drawing engine takes care of clippingit is quite a bit easier to let it fall through. Building--------I have added a makefile.vc to the shapelib distribution.  After you haveunpacked the shapefile you should have a shapelib subdirectory.  If youcd to that directory, and enter ``nmake -f makefile.vc'' in a DOS windowyou should be able to build everything with VC++ (assuming it is properlyinstalled and in your path). You can also create a project in VC just including the files shpopen.c, shptree.c and shptreedump.c, building as a Win32 consoleapplication. For your convenience I am including prebuild .obj files, and .exe filesin the distribution.