> Andrew - > > I got the documentation for the grid engine from MapInfo (a file named > grideng30.exe containing 2 word files). It did contain documentation for > the Grid API functions, but missed a description of the various > C-structures (or records in Pascal) used by the API. > > It it possible for you to publish the missing documentation for these > C-structures, or - best of all - a simple C or Delphi (working) example > with source code.?? > > regards > > Bo Thomsen > GeoConsult I/S > Denmark > > > > > -----Oprindelig meddelelse----- > Fra: [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]] > Sendt: 5. juni 2000 18:46 > Til: [EMAIL PROTECTED] > Cc: [EMAIL PROTECTED] > Emne: Re: MI Grid file > > >Does anyone have experience of using either large grid files or tiled > grid > >files to represent, for example, elevation data? > > We have some. > > >We're trying to determine the best way to distribute DEM data for use by > >MapInfo Professional (without add-in's). Options we've considered are: > (1) > >points (2) square cells as regions and (3) .mig files. Given around 10 > >million readings, option 1 would be bulky and option 2 even more so! > > >Specific questions on .mig files- (1) what is the size limit? (2) is the > >limit related to the IDW algorithm? (3) are there alternative > algorithms? > >(4) has anyone written a .mig loader, say from a point file? > > 1. Based on the definition of these functions from the API, the size limit > appears to be about 2,147,483,648 x 2,147,483,648, but I'm sure practical > limitations become apparent long before that. > > BOOL GRIDENGFUNCTION GE_GetContinuousValue(GE_HGRID hGrid, > long lCol, long lRow, double *pdValue, unsigned char *puchIsNull); > > BOOL GRIDENGFUNCTION GE_GetDimensions(GE_HGRID hGrid, long *plWidth, > long *plHeight); > > BOOL GRIDENGFUNCTION GE_WriteContinuousValue(GE_HGRID hGrid, > long lCol, long lRow, double dValue); > > 2. No, the IDW algorithm is just one way to create a grid file. > > 3. I know that ESTI-Map in Moscow has written a TIN-based interpolator, > and Mercator Geosystems has others. > > 4. MapInfo Professional 5.5 (and now 6.0) includes a DEM2GRID utility. > > The complete API for the Grid Engine is available upon request. > > ---------------------------------------------------------------------- > To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put > "unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED] ---------------------------------------------------------------------- To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
