So how does the new ACS tools work?

Well, with the advent of new ACS functionaliity in V8i many folks have been asking about it, and how does it exactly work?  Let's start with some basics:

You can define new x‐ and y‐ axes in your design plane and save them as an auxiliary coordinate system (ACS). You can define several auxiliary coordinate systems and quickly choose any of them to use. At any time, you can make one ACS active per view.

ACS's are now View Independent, that is to say you can have a different ACS in each view.

Auxiliary coordinate systems can be particularly helpful in 3D design, where they facilitate placing elements on planes at different depths and orientations. By using an ACS that corresponds to the location and orientation of a particular element, you can enter data points relative to that element rather than the global origin.

But do not overlook their value in 2D, when you wish to save a specific rotation.


  1. The active ACS for a view is NEVER a named ACS, it is a COPY. You can set it from a named ACS and as long it still matches the named ACS it will display the name to show where it originated from. For example, set a named ACS for a view, then change it, by using the AccuDraw shortcuts RA, E, Define ACS by Points tool, etc. Only the active ACS for the view is changed and the connection with the named ACS is broken (the view becomes unnamed). Otherwise, you would have to be very careful not to inadvertently redefine
    your carefully setup named ACS.
  2. The View Independent toggle (right click on a named ACS in the ACS dialog to select command) is a little different. It is currently only a property of the active ACS, not a named ACS. As long as the other settings are the same you can toggle it on/off without breaking the connection to the named ACS, but if it is left view
    independent MicroStation will stop showing the name when you re‐open the file because the active ACS would have been saved without a fixed rotation. With a view independent ACS the xy‐plane is always aligned parallel to the view at the defined depth or the equivalent to active depth in V8i.

So the main thing to understand is that a view's ACS is completely independent of any named ACS, the name is just a helpful hint as to how it was setup that is only valid as long as nothing is changed.

ACS and Depth Lock

MicroStation V8i no longer has a Depth Lock. It is replaced by the ACS Plane Lock. The ACS always defines your working plane now, it is not going to be some static thing that you just leave at 0,0,0 with an identity rotation and never use.

To mimic depth lock you can setup a view independent ACS, which is the default for files that did not have ACS Plane Lock enabled and what the set active depth tool now does. Then turn on ACS Plane Snap from Settings > Locks > ACS Plane and ACS Plane Snap or use AccuDraw shortcuts LP, LA and/or LS.

Some Frequently Asked Questions:

  1. Do I need to set up view oriented ACS for each rotated view?
    You certainly can, you could have an ACS for your elevation view that is always front and your plan view that is always top, etc. However, if you typically work with a single view and frequently switch between standard
    rotations to draw on different planes aligned to the view, changing the ACS would get tedious. A view's ACS can now specify that it is view independent, in other words, defines a point that a plane aligned with the
    view passes through, effectively the active depth concept but without having to worry about viewing operations inadvertently changing it out from under you. If you have display of the ACS enabled for a view, a view independent ACS displays the triad arrows with a dotted style instead of solid.
  2. How does this affect the coordinate readout in the Status Bar.
    First, use Running Coordinates (right click onthe Status Bar and select). Then by left clicking on the Running Coordinates box in the Status Bar you can choose to display: Position, Delta, View Delta, Distance, ACS Position, or ACS Delta.
  3. I do heavily rely on view active depth, for rotating views. I would have thought that when no ACS is enabled then the active depth and depth lock should work as before.
    The ACS is effectively always enabled. ACS Plane Lock now just controls whether viewing operations and AccuDraw shortcuts for T, F, S are relative to the design coordinates or the ACS. It also controls whether the
    ACS scale will be used (in the case where you have explicitly set a scale other than 1.0 for your ACS).
  4. We use SET TPMODE LOCATE how does this affect us?
    It should not affect you. To always report coordinates relative to the global origin, use tpmode locate. If you do not want the snap point projected to the active ACS Plane (i.e. active depth) turn off ACS Plane
    Snap just as you would have had to turn off Depth Lock in previous versions. Use TPMODE ACSLOCATE only if you set a specific ACS for you view, and the expectation here is that these users will use the ACS tools
    and ACS dialog and not use the old active depth tools. You can also change your mode with Running Coordinates.
  5. Do I need to use ACS Plane Lock and ACS Plane Snap Lock always in my workflow now?
    The ACS locks is for someone who has setup an explict ACS to a meaningful location/orientation. ACS Plane Lock is not needed to control whether un‐snapped points are projected to the ACS Plane, that always
    happens now.
  6. How do I save my ACS's?
    ACS's are saved with Save Settings.

Well, there is much more here like AccuDraw and ACS's and using the ACS tools ... more on that in later blog ... happy drafting!