Summit and CAD/GIS-side SI Clip Settings: Why are there two settings that seem to be the same? Which one should I use?
by Alissa Oder
SI = Summit's SuperImposition
CAD/GIS side = AutoCAD, MicroStation, ArcGIS ArcMap, ArcGIS Pro, Global Mapper, or third-party API
There may be SI-area-limiting settings offered in both Summit and in the CAD/GIS application. Which setting should you use when they are seeminly the same? In the case of a third-party API using Summit, there may not be a Clip SI setting, so it's obvious that you should use Summit's SI User Bounds to limit the amount of SI vectors in memory; however, if the CAD/GIS interface offers SI Clip settings, it's a little more difficult to know which setting to use. It may seem confusing, but both settings are necessary and useful in their own way.
So what's the difference between Summit's SI User Bounds…
…and these CAD/GIS-side SI Clip settings?
Which settings to use could depend on how dense the vectors are and how large an area they cover outside the current model's stereo area.
A.) If you only use the CAD/GIS-side Clip SI option, only part of the vector set is initially loaded into SI memory. Providing you only want to clip to the model's stereo area, it is not necessary to further use the Summit-side SI User Bounds, because the vectors to clip are not even there.
In order to use the CAD/GIS-side Clip SI Option, it must actually be offered there. It may not be offered by some API applications.
Using the CAD/GIS-side Clip SI option is useful as follows:
B.) If you use only the Summit-side SI User Bounds, all the vectors are initially loaded into SI memory, and then Summit's SI User Bounds must do all the calculations to clip them. After clipping them, memory use is reduced, and performance will be faster. Depending on the vector set and area of interest, this initial loading and subsequent clipping could be slower than A. above.
Using only the Summit-side SI User Bounds could be useful in the following cases:
C.) Sometimes both options could be useful together. If you have the CAD/GIS-side Clip SI option on, it will initially limit the SI vectors to the model area. Now if you want an even smaller area of SI, for example ¼ of the model, you could use Summit's SI User Bounds to remove more vectors from memory. There would be the initial CAD-side calculation to remove vectors outside the model (saving some memory initially), then there would be an SI-side calculation to remove more vectors from memory. This could be slower than A. at first; however, this is usually done to reduce overall SI memory use, and could be faster for some very dense data sets.
Using both settings could be useful in the following cases:
There may be other seemingly duplicate settings, such as “SI On” or “Show Points” on both sides. The rule is: If the setting is offered on the CAD/GIS side, use it. Otherwise use Summit's setting.
Will it hurt if you forget which one to use? No. It may simply be a little slower to calculate the change to SI.
Anchorage, Alaska, USA. September 22, 2015 – DAT/EM Systems International® welcomes Jennifer Dowling to the technical support team. Dowling has over 25 years of experience in the GIST industry with jobs in cartography, surveying, hydrography and more.
Jennifer Dowling is a 2014 Master's Degree graduate in the GIST Program at the University of Southern California and expects to earn her graduate certificate in Geospatial Intelligence in December 2015. She was a hydrographer in NOAA's Commissioned Officer Corps (2000-2008) where she collected, processed and prepared hydrographic data for inclusion on nautical charts and conducted geodetic field work to establish and recover ground control data to support nautical and aeronautical charting. She was also a National Geodetic Survey liaison in Alaska where she provided guidance and field support for local surveyors. Dowling's first career was as a cartographer with USGS in Denver (1989-1996) and Anchorage (1996-2000). She was involved in all aspects of topographic mapping, including project planning, fieldwork, photogrammetry, map finishing, and distribution. She also converted published topographic maps to digital format and assisted scientists in digital map collection.
“Jennifer Dowling has an extensive cartographic background with special expertise in geospatial intelligence,” says Jeffrey Yates, DAT/EM General Manager. “She is the perfect addition to our technical support staff.”
Dowling's wide array of photogrammetric software expertise will aid her in assisting our clients with their technical questions.
About DAT/EM Systems International. DAT/EM Systems International, located in Anchorage, Alaska, USA, has been developing photogrammetric software since 1987. DAT/EM specializes in 3D stereo viewing and feature data collection software. Its products include the Summit Evolution digital stereoplotter and proprietary Capture interfaces that allow Summit Evolution to digitize directly into MicroStation®, AutoCAD®, ArcGIS® or GlobalMapper®. For more information, please visit DAT/EM's website at www.datem.com or email email@example.com.