Using Masks in AutoCAD to cover underlying features (hiding transparency)

In most programs, hiding underlying features is easy, but, in AutoCAD’s polygon/polyline based interface it is less easy. This article will outline three methods for whiteing out backgrounds in AutoCAD.

1) Text Masking: If you want text to have a black background (ie. White), enter the mtext properties, select “background mask” and click to select a mask that matches your background color (which may or may not be white). You can also use this command to select a colour of your choice to mask the text. Background masking can also work for other types of features and will be discussed at length in a future article.

2) The ‘wipeout’ command: this works well for an areal feature, like a polygon that surrounds text ie. Text in a box. Type the command wipeout, hit p for polyline, select the box surrounding your text in AutoCAD, then choose not to erase the box (obviously). What this will do is cover all of the features behind the feature you have selected. One draw back to this command, I find, is that when you re-open the document later, a bug often shifts the layer ordering, messing up what you have done. Silly AutoCAD!

3) Finally, when all else fails, a simple hatch can cure your AutoCAD woes. Select the polyline you wish to hide the interior of, type hatch (or h for short), choose solid color, then select the colour that matches your background by default.

Well, these three somewhat annoying to use commands are the only way, that I know of, to grey out background items in AutoCAD 2008. You should now be able to do away with transparencies in all of your CAD .dwg files. Hopefully.

ArcGIS Tutorial: Giving Legend Elements the Same Transparency as the Polygons in the Data View

If you're like me and you often have to digitize landuse areas and have to overlay them on an orthoimage, then this guide might help you with a common issue in ArcGIS. When you edit a polygonal layer and manually digitize a land use (with heads up digitization), you usually want to make it transparent so you can see the airphoto/satellite image underneath it. The problem with ArcGIS 9.2 (and 9.0, 9.1) is when you generate a legend, the legend items do not show the same transparency.

So, for instance, if you use red to indicated a black parking lot in ArcGIS, then give the red shapefile 50% transparency. The actual, on screen, colour is kind of a very dark red. However, in the Legend you see bright red, as if there was no transparency.

To fix this, here is the solution:

1) Make sure you have the transparencies and colors as you want them, this ArcGIS procedure is semi-permanent (ie. time consuming and difficult to undo).
2) First, you make sure the eye dropper tool is enabled and on a toolbar (go to customize> commands > page layout to add it to a tool menu).
3) Use the eye dropper to select the color in the ArcMap viewport that you wish to change the legend item to. It will save it to your colour palette as a standard ArcGIS color (but only for the .mxd document you are working on). Do the same for all the layers you wish to correct the color for.
4) Now you have the colour information stored for each of the transparent layers you wish to update in the legend. Click on the legend, right click and select "Convert to Graphics". This will break the legend into individual editable units
5) Select the Box of color that you wish to correct to the transparent color.
6) Use the bucket fill tool - found in the drawing menu - to change the colour of each box to their respective corrected transparent colors.
7) At this point, each legend item should be corrected and we have succesfully worked around this annoying ArcGIS issue.