ããã«ã¡ã¯
æ°äºãããè£è¶³ãããå
容ã§ããã誀ã£ãèšè¿°ã«ãªã£ãŠãããŸãã
å©çšã§ããé¢æ°çã«ã€ããŠè©³çŽ°ã¯ãã£ãŒã«ãèšç®æ©å
ã§ç¢ºèªã§ããŸãã
$area ã¯
以äžã®ããã«èšãããŠããŸãã
> å°ç©ã®é¢ç©ãè¿ããŸãããã®é¢æ°ã§èšç®ãããé¢ç©ã«ã¯ãçŸåšã®ãããžã§ã¯ãã®
> æ¥åäœèšå®ãšé¢ç©åäœèšå®ã®äž¡æ¹ãåæ ãããŸããäŸãã°ããããžã§ã¯ãã«
> å転æ¥åäœãèšå®ãããŠããå Žåãæ¥åäœé¢ç©ã«ãªããèšå®ãããŠããªãå Žåã
> å¹³é¢äžã®é¢ç©ã«ãªããŸãã
ã€ãŸããããžã§ã¯ã CRS ïŒ QGIS ãŠã£ã³ããŠå³äžã«èšèŒãããŠãã CRS ïŒãšããŠ
ã EPSG:4326 WGS84 ããèšå®ãããŠããå Žå㯠WGS84 æ¥åäœäžã§ã®é¢ç©ãèšç®ãããŸããã
ã EPSG:6677 JGD2011 å¹³é¢çŽè§åº§æšç³»9ç³»ããèšå®ãããŠããå Žå㯠GRS80 æ¥åäœäžã§ã®
é¢ç©ãšãªããŸãïŒ JGD2011 ã§æ¡çšããŠããæ¥åäœã GRS80 ã§ããããïŒã
ãã®éã«ã¯ïŒãããžã§ã¯ãããããã£ã®èšå®ã«äŸããŸããããã©ã«ãã®èšå®å€ã§ã¯ïŒ
ã¡ãŒãã«åäœã§æ£ç¢ºã«èšç®ãããŸãã
ããã¯å°ç©ïŒã¬ã€ã€ïŒã®åº§æšç³»ãã緯床çµåºŠåº§æšç³»ã§ãã£ãŠããé¢ç©ã®æªã¿ã倧ããª
ã¡ã«ã«ãã«å³æ³ãªã©ã§ãã£ãŠãåæ§ã§ãã®ã§ãåºæ¬çã«åé¡ã¯ãããŸããã
ãªãèšç®åŒã area($geometry) ã§ããšãä»®ã«å°ç©ïŒã¬ã€ã€ïŒã緯床çµåºŠåº§æšç³»ã®å Žåã«ã¯ã
é¢ç©ã®åäœã¯å¹³æ¹åºŠãšãªããŸãã
ããã¯ãããšããŠããçµåºŠå·®1床ããšã緯床差1床ãã¯ãåãã1床ãã§ãè·é¢ã¯ç°ãªããŸãã
ãããã€å³ãšã¯ãåäžã®ç¹ãæè¿åãšããé åã瀺ããã®ã§ãã®ã§ããããã€ããªãŽã³ã
æ±ããéã«ãã床ãåäœã§è§£æãããšäžé©åãªçµæãåŸãããããšãèããããŸãã
ãããã€ããªãŽã³ãæ±ããåã®ç¹ã®æ®µéã§ãå¹³é¢çŽè§åº§æšç³»çã«åæ圱ããŠãããæ¹ã
ããããããšæããŸãã
çµ±èšéã®ç®åºã§ããã HTML 圢åŒã§ã®ã¬ããŒãã§ãããã°ããã»ã·ã³ã°ããŒã«ãã
ãå±æ§ã®åºæ¬çµ±èšéããå±æ§å€ã«ä»äžãããå Žåã¯ãéèšããªã©ãå©çšã§ããŸãã