There are two methods to select boundaries when using Hatch in CAD: Pick Points and Select Objects. Many people can’t tell the difference and most of them choose Pick Points.

 So when to use Pick Points and when to use Select Objects? I made a simple comparison using a couple of examples, I guess you’ll have some idea after reading this.

The above are cases in which the Pick Points method has clearly specify the area to be hatched, it’s very easy and applies to most cases; Select Objects are relatively more demanding: for the boundary, closed polyline is better, if not a polyline, then it needs to form a closed area. Hatch will also apply to intersected but not closed line, but the result would be strange. As a result, most people choose the Pick Points method to hatch.

From the picture above, we can see that in some cases, the Pick Points method has the same effect as the Select Objects method while in other cases, we need to ignore other line in the closed polyline and directly point selecting polyline is inevitably the best option.

Using which method to hatch requires knowing the effect of the two methods in a different situation and the calculation method of the two methods. When using the Pick Points method to select an area to hatch, the CAD software will search and calculate within the viewport and will generate a reasonable range. When there are many graphics in the viewport and if the graphics are complex, for example, there are many circles, arc, spline and there are also many intersections, nest, slowing the calculation process. In the lower version of CAD, it asks you whether to continue for there are many objects and heavy calculation burden. Higher version has optimized this but it still takes long. But selecting objects would be different, for the CAD system only need to calculate if the selected objects have formed closed area or nested or not, which makes the calculation less heavy. So when the graphics are complex and if it has met the needs to select objects, we’d better use Select Objects method; If the only method available is Pick Points, we can zoom in the viewport as much as possible and make fewer objects shown in the viewport, or we can create boundary sets by selecting objects and then pick points. As shown in the following picture, the default boundary set is the current viewport, the purpose of zooming in the viewport and creating boundary set is to decrease the number of graphics involved in calculation.