I recently came across a site called smart blocks http://www.smartblocks.co.uk/ that allows you to place blocks in drawings that automatically mask out the line work behind them when they are placed within a file. AutoCAD has a few more tools available to mask out information (the WIPEOUT command and XCLIP being two of them). Microstation users are stuck with having to use fences and the clip mask tool for references which can be tedious to say the least especially if you are using a lot of cells within the drawing.

In this post I am going to create a cell in Microstation that will mask out background elements. For this I am going to use a tree cell that we commonly use in our drawings. I started by placing the cell in a new drawing and dropping it to geometry.

Now we need to use the create region tool. Set the tool to use an opaque fill type and set the fill colour to BG (Background) also turn on locate interior shapes and keep original so that it retains an outline. As we set the fill colour to be BG this will mask out elements behind the cell when it is placed down.

You might notice that the lines around the edge of the tree appear faint, to fix this select the lines and then go to the Edit menu and select Bring to Front. This brings the lines over the top of the background fill.

Now create the cell by attaching an existing or creating a new cell library, defining a cell origin and selecting the elements and then click the create button.

Now when this cell is placed down in a drawing background elements will be masked out.