March 25, 2008

GIS and CAD Signs, Symbols and Fonts

While driving to Oklahoma for the National Christian Homeschool basketball championships this month, I and three other parents rotated driving duties for the 21hr non-stop trip along much of Route 66 (I-40) from California. I pulled shifts in the overnight hours getting to watch the sunrise over the steering wheel, and one shift included a morning snow storm near Flagstaff on the way home. My daughter snapped the accompanying picture in the middle of the night at one of our driver rotation stops somewhere in No-Where New Mexico. Looks like the sign has seen a hard life and was even reused from some signage in days gone by.

At the tournament our girls were one of the youngest teams in the 18yr old and under division and won 3 of their 5 tournament games to finish 21st. Finishing up one spot higher than their initial ranking with a loss to the Indiana state champions and a good team from Missouri that fielded a talented All-American player. We met coaches, parents and young people from all around the country. We had a nice time talking with one team from Wisconsin earlier in the week that we ended playing in our last game. We even sat with them at the awards ceremony. We asked the Wisconsin girls if they had enjoyed meeting other girls from around the country, their point guard gave us a troubled and confused look and responded, 'Girls!?... we’re meeting BOYS!'

One of the primary point symbol types supported by ArcMap is the use of true type-fonts as marker symbols. I use true-type marker symbols in both ArcGIS and CAD when I want the symbols to be the same in both the CAD and GIS versions of converted data. Although I have more flexibility in the creation of cells and blocks for CAD symbology, the ability to reference existing ArcGIS marker symbols in a true-type font can be easier than recreating a CAD symbol set of the GIS marker symbols for interoperability. The trick to getting the ESRI marker symbols in CAD is to create CAD text rather than points. The ArcGIS Export to CAD tool available with an ArcView license, allows me to export point features as CAD text by overriding the default [CADType] with TEXT and then specifying the Unicode character or formatting code string in the text value stored in the [TxtValue] field of the point feature layer’s table.

I can specify the right symbol with CAD formatting syntax in the text string recognized by CAD (ie: [\U+0073], or use the keyboard short cut to type in the actual Unicode value in the string once I’ve done a little research to find the values of the symbols I want to use. Finally to get the right symbol in CAD I need to have access to the same true type font in ArcGIS as in the CAD system. Export to CAD will then use the true-type font referenced by the [TxtFont] field that I include in the feature layer attribute table or an existing CAD font style based on that true-type font that I could reference in a field called [TxtStyle].

Luckily we don’t have to travel for the final games of the year. Wish us luck as we play this week for the California State Tournament Championship.
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