#CLOCKWISE COUNTERCLOCKWISE INSTALL#

The exterior boundary LinearRing defines the “top” of the surface which is the side of the surface from which the exterior boundary appears to traverse the boundary in a counter clockwise direction. Each interior boundary defines a hole in the Polygon.

interior rings (holes): clockwise direction.Ī Polygon is a planar Surface defined by 1 exterior boundary and 0 or more interior boundaries.

Here is an overview on outer ring directions of polygons in various formats by their specifications:Īlso used in WKT/GML/KML and various SQL implementations: Determining which of those two areas is the bigger one is possible, but still leaves the ambiguity. Ring (boundary) directions are needed to prevent ambiguities for geographic coordinate systems that cover a finite surface, since the boundary would define two areas, one left and one right of the boundary along it's direction. One solution is computing the area of each polygon and, if I remember correctly, if it is positive the order is clockwise and if negative the order is counterclockwise.Īrea computation is not an intensive task, so it will not slow my plugin so much.īut in the special case of QGIS, anybody knows if it stores the polygons clockwise or counterclockwise, regardless the order in the original source?īy now I'm working with ESRI shapefiles and the coordinates in layer.getFeatures().geometry().asPolygon() are stored in clockwise for the outer border and counterclockwise for the holes, i. As I need to check the angles between consecutive sides of polygons using their azimuths I need to known if the order is clockwise. My purpose is to write a plugin for QGIS, but the source of data can be ESRI shapefiles or other formats. Is the clockwise order only for ESRI shapefiles or for general GIS formats?Īnd what about the internal representation for a GIS software?įor example, if I use QGIS and I read a *.shp containing polygons I suppose the internal representation of the outer bound is clockwise as in the original shapefile, but what about for all the file formats supported by QGIS?Īnd in the case there exists a file format with polygons stored in counterclockwise, if these files are loaded in QGIS, ArcGIS, etc., is the orientation changed internally, so if I read the data using PyQGIS, for example, the polygons are clockwise ordered?

That question was answered ( Are polygons stored clockwise or counterclockwise in a shapefile?) and it was also answered in an old post ( Polygon creation (Clockwise rotation or not))īut now my question is more general, and I don't know if it has an unique answer. Thanks for any input as always Larry.Two days ago I asked a question about the internal storing order for the vertices of a polygon in ESRI shapefiles.

#CLOCKWISE COUNTERCLOCKWISE INSTALL#

Wondering if there's a gear box that will change counter clockwise rotation to a clockwise rotation.I have a older massey 1655 with a front mount snowblower and installed it onto my newer massey gc2300 to my surprise after taking time to make a quick hitch etc and install it onto the 2300 I found out that the blower turns backwards.So the only other thing I can do is see if there's such a thing as a gear box that will do that.The pto on the 2300 turns counter clockwise and the 1655 turns clockwise.So the only thing I can do is change the rotation to clockwise by using a gear box.I had thought about cutting the chute off and putting it onto the other side and change the augers from one side to the other but after changing the augers to push the snow to the center it still wouldn't work because they'd be trying to push the snow away from the blower rather then towards it.So anyone have any thoughts on what or where to get a gear box like that.Right now I mounted the blower back onto the 1655 so that if and when it snows I'll have a tractor to blow snow with.What I'am hoping is to beable to use the new one as I made a cab and put heater into the cab as well.The old 1655 has a cab but its not heated I've used it for years like that but like all of us it would be nice to sit in a heated cab.

Clockwise counterclockwise