I am new to GIS area and also new to any software that can modify the GIS.
I am currently working with South Australia map I have download from Australian census site. I am using QGIS to load the shapefile and also do any modification.
Here is a link to download the geo datasource from Australian Government Site
My problem is when I have downloaded this south australia (SA - State of Australia), near the boundary of the state, I see there two polygons on top of each other fully overlapping. I reduced the fill opacity to 50% so where you see dark yellow colour those are overlapping polygons. It looks like some rectangle polygons on top of real suburb's outline. I dont know why it is like that ? And how can I get read of this.
Also I want to know how can merge (or dissolve) features (polygons) in same layer. Everytime I dissolve it create on new layer.