# [geos-devel] Buffer Problem

chirag soni chirag19 at yahoo.com
Mon Jan 7 07:37:56 EST 2008

```Hello Friends,
I have problem with buffer operation which has same input geometry with three different distance. I have three cases for buffer operation as bellow. Case 1 and Case 3 gives perfect result.But Case 2 has some problem it sould give Multipolygon with two circular polygon like Case3. Case 2 only return one polygon instead of two polygon. there is some problem in buffer operation. please help me. It is happening for all type of Multi Geometry.
------------------------------------------------------------------------
Case : 1
------------------------------------------------------------------------
Input Geometry = MULTIPOINT(-123.264337 1.80652,-10.817308 17.740385)
Buffer Distance = 60.000000
Status = Working Ok
Result Output Geometry  = POLYGON ((-69.7683199416213710 28.3909394912853800, -69.6644248241938730 29.4458043209674900, -66.2500799506772890 40.7013909419051810, -60.7054847381528480 51.0745989811759390, -53.2437148711930350 60.1667918711926720, -44.1515219811763440 67.6285617381525700, -33.7783139419056230 73.1731569506771110, -22.5227273209679310 76.5875018241937790, -10.8173080000002240 77.7403850000000030, 0.8881113209674876 76.5875018241938650, 12.1436979419052020 73.1731569506772810, 22.5169059811759770 67.6285617381528110, 31.6090988711927250 60.1667918711929700, 39.0708687381526260 51.0745989811762660, 44.6154639506771530 40.7013909419055220, 48.0298088241937930 29.4458043209678270, 49.1826920000000030 17.7403850000000000, 48.0298088241938360 6.0349656790323145, 44.6154639506772240 -5.2206209419053629, 39.0708687381527400 -15.5938289811761060, 31.6090988711928880 -24.6860218711928180, 22.5169059811761830 -32.1477917381526770, 12.1436979419054510
-37.6923869506771750, 0.8881113209677771 -41.1067318241938150, -10.8173079999999030 -42.2596149999999970, -22.5227273209675900 -41.1067318241938440, -33.7783139419052670 -37.6923869506772460, -44.1515219811760320 -32.1477917381527760, -53.2437148711927510 -24.6860218711929460, -60.7054847381526340 -15.5938289811762550, -64.3133250583786380 -8.8440344912853597, -64.4172201758061650 -9.8988993209676863, -67.8315650493227760 -21.1544859419053640, -73.3761602618472610 -31.5276939811761070, -80.8379301288071020 -40.6198868711928180, -89.9301230188238210 -48.0816567381526810, -100.3033310580945400 -53.6262519506771800, -111.5589176790322200 -57.0405968241938130, -123.2643369999999000 -58.1934800000000010, -134.9697563209675800 -57.0405968241938480, -146.2253429419052700 -53.6262519506772510, -156.5985509811760300 -48.0816567381527800, -165.6907438711927500 -40.6198868711929460, -173.1525137381526300 -31.5276939811762560, -178.6971089506771500
-21.1544859419055410, -182.1114538241938000 -9.8988993209678746, -183.2643370000000100 1.8065199999998061, -182.1114538241938600 13.5119393209674930, -178.6971089506772900 24.7675259419051810, -173.1525137381528300 35.1407339811759340, -165.6907438711930400 44.2329268711926740, -156.5985509811763400 51.6946967381525650, -146.2253429419056100 57.2392919506771070, -134.9697563209679200 60.6536368241937750, -123.2643370000002200 61.8065199999999990, -111.5589176790325000 60.6536368241938670, -100.3033310580948000 57.2392919506772840, -89.9301230188240200 51.6946967381528140, -80.8379301288072720 44.2329268711929730, -73.3761602618473600 35.1407339811762610, -69.7683199416213710 28.3909394912853800))

------------------------------------------------------------------------
Case : 2
------------------------------------------------------------------------
Input Geometry = MULTIPOINT(-123.264337 1.80652,-10.817308 17.740385)
Buffer Distance = 40.000000
Status = Notwroking Properly
Result Output Geometry  = POLYGON ((29.1826919999999990 17.7403850000000000, 28.4141032161292240 9.9367721193548775, 26.1378733004514780 2.4330477053964241, 22.4414764921018240 -4.4824243207840695, 17.4669632474619230 -10.5438862474618770, 11.4055013207841220 -15.5183994921017890, 4.4900292946036338 -19.2147963004514500, -3.0136951193548152 -21.4910262161292100, -10.8173079999999370 -22.2596150000000000, -18.6209208806450590 -21.4910262161292320, -26.1246452946035140 -19.2147963004515000, -33.0401173207840200 -15.5183994921018530, -39.1015792474618420 -10.5438862474619660, -44.0760924921017510 -4.4824243207841725, -47.7724893004514260 2.4330477053963069, -50.0487192161292000 9.9367721193547514, -50.8173079999999970 17.7403849999998720, -50.0487192161292430 25.5439978806449940, -47.7724893004515250 33.0477222946034530, -44.0760924921018930 39.9631943207839560, -39.1015792474620200 46.0246562474617780, -33.0401173207842330 50.9991694921017140,
-26.1246452946037450 54.6955663004514040, -18.6209208806452860 56.9717962161291920, -10.8173080000001500 57.7403850000000030, -3.0136951193550079 56.9717962161292490, 4.4900292946034686 54.6955663004515170, 11.4055013207839830 50.9991694921018710, 17.4669632474618160 46.0246562474619840, 22.4414764921017530 39.9631943207841760, 26.1378733004514350 33.0477222946036800, 28.4141032161292020 25.5439978806452180, 29.1826919999999990 17.7403850000000000))

------------------------------------------------------------------------
Case : 3
------------------------------------------------------------------------
Input Geometry = MULTIPOINT(-123.264337 1.80652,-10.817308 17.740385)
Buffer Distance = 10.000000
Status = Working Ok
Result Output Geometry  = MULTIPOLYGON (((-0.8173080000000006 17.7403850000000000, -1.0094551959676945 15.7894817798387180, -1.5785126748871310 13.9135506763491050, -2.5026118769745445 12.1846826698039830, -3.7462401881345198 10.6693171881345310, -5.2616056698039699 9.4256888769745526, -6.9904736763490920 8.5015896748871373, -8.8664047798387049 7.9325321959676973, -10.8173079999999850 7.7403849999999998, -12.7682112201612660 7.9325321959676920, -14.6441423236508790 8.5015896748871249, -16.3730103301960060 9.4256888769745366, -17.8883758118654580 10.6693171881345080, -19.1320041230254390 12.1846826698039570, -20.0561033251128580 13.9135506763490770, -20.6251608040322980 15.7894817798386880, -20.8173080000000010 17.7403849999999680, -20.6251608040323120 19.6912882201612480, -20.0561033251128830 21.5672193236508640, -19.1320041230254740 23.2960873301959880, -17.8883758118655050 24.8114528118654430, -16.3730103301960600 26.0550811230254280,
-14.6441423236509360 26.9791803251128500, -12.7682112201613230 27.5482378040322970, -10.8173080000000380 27.7403850000000000, -8.8664047798387529 27.5482378040323110, -6.9904736763491329 26.9791803251128780, -5.2616056698040046 26.0550811230254670, -3.7462401881345464 24.8114528118654970, -2.5026118769745622 23.2960873301960450, -1.5785126748871416 21.5672193236509210, -1.0094551959676998 19.6912882201613040, -0.8173080000000006 17.7403850000000000)), ((-113.2643370000000000 1.8065199999999999, -113.4564841959676900 -0.1443832201612809, -114.0255416748871200 -2.0203143236508940, -114.9496408769745400 -3.7491823301960174, -116.1932691881345200 -5.2645478118654694, -117.7086346698039700 -6.5081761230254473, -119.4375026763490800 -7.4322753251128626, -121.3134337798387000 -8.0013328040323017, -123.2643369999999800 -8.1934800000000010, -125.2152402201612600 -8.0013328040323088, -127.0911713236508800 -7.4322753251128750, -128.8200393301960100
-6.5081761230254633, -130.3354048118654600 -5.2645478118654916, -131.5790331230254300 -3.7491823301960432, -132.5031323251128600 -2.0203143236509233, -133.0721898040322900 -0.1443832201613122, -133.2643370000000100 1.8065199999999675, -133.0721898040323200 3.7574232201612485, -132.5031323251128900 5.6333543236508632, -131.5790331230254800 7.3622223301959897, -130.3354048118655200 8.8775878118654461, -128.8200393301960700 10.1212161230254270, -127.0911713236509400 11.0453153251128530, -125.2152402201613200 11.6143728040322960, -123.2643370000000400 11.8065199999999990, -121.3134337798387500 11.6143728040323100, -119.4375026763491300 11.0453153251128810, -117.7086346698040000 10.1212161230254690, -116.1932691881345400 8.8775878118654958, -114.9496408769745600 7.3622223301960439, -114.0255416748871400 5.6333543236509200, -113.4564841959677000 3.7574232201613045, -113.2643370000000000 1.8065199999999999)))

Chirag Soni

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