2 - Saving and Loading Moves - Technical Overview

Supported Firmwares:

Loading and Saving Moves are supported on our RC008_XXX releases of firmware. Find this out on our Firmware Down load page.

Concepts

Real-World Alignment (RWA)

Real-World Alignment is the act of calibrating your ST4 so that it knows where it is in relation to the world. There are two parts of real-world alignment:

1. RWA Part 1 - Positioning your camera/slider at the right latitude/longitude and altitude to a very high degree of accuracy.  Millimeters matter here.  

   • If shooting on a tripod this is doing your best to put make sure you camera is the right 3D point in space.  The best case scenario is if you were working off of a fixed, permanent mount like a cement block with a 3/8-16 stud sticking out of it where you could mount your gear, but short of that a tripod over a survey mark with a plum bob exactly 28 inches up is a close second
   • If shooting on a slider, you need all the positing accuracy lat,long,alt, but twice for both ends of the slider to insure your linear movement is the same. 
     
     Getting this right is an art.  This is not something technology can help you with with most shots.  Break out the shooting journal, take copious notes and setup pictures and practice. Did we mention this is an art!  
     
     
     
2. RWA Part 2 - Calibrating the ST4 to the real world for Pan, Tilt, Slide and Focus -There are three ways in which a user can complete this calibration. The first and most recommended way to do this is to set a Home Reference before saving or loading a move file.
   
   

   • A Home Reference is a point in the real world that is reproduceable independent of time of day/year. This reference is separate from the shot and does not necessarily have to be within your shot.

     • • An example of a good Home Reference would be the tip top of an antenna hundreds of feet, or miles away, a fence post in or out of your shot, top of a dead tree that you sure isn't going to fall down
       • An example of bad Home Reference point is - a star, the sky, tree leaves, and any near field object that is close to your camera. With near objects small translation misalignment of your camera/slider position result in bigger alignment issues.
         
         
   • The other two references that can be used to setup the Real-World Alignment is a Start Point Reference or an End Point Reference. As the name suggests these references are the Start Frame of your shot or the End Frame of your shot. These references are used primarily in the Basic Save/Load workflow. However, this reference could also be useful in the scenario where only the Start or End Frame of your move is critical to hit. For example, your if move ends on a location like a building that has many sharp points you could mark down where the top left focus point hits the third floor widow pane third panel from the left.

• • • • An example of a good start or end point reference is where you have a clear and sharp point that aligns well with something in your viewfinder like a point on a ridge.
      • An example of a bad start or end point reference is the sky, a waterfall, the ocean, a car, or anything that will be occluded or change between shots.

Project ID (PID)

A Project ID (PID) is a 3-character identifier used to organize the Shots/Move Files. This is essentially a named folder. Your existing projects can be found on your SD Card under the MoveFiles/PID folder. This folder is created upon saving your first move to an SD Card. Currently a user can create 20 unique project IDs through the ST4 interface. It is not recommended to add project IDs to the SD Card manually or to change the names once created. (See Known Issues for more information).

ST4 Move File

An ST4 move file contains all the information needed to load up and replay a move in reference to your Real-World Alignment.  An ST4 Move File is are stored on an SD Card under the folder structure MoveFiles/PID.  Currently you can add 20 move files to a single Project ID. This structure allows for a total of 400 unique moves to be saved/retrieved to a single SD Card. Most move files include all setup variable as well as the trajectory file.  While some of the header of the file are human readable, none of the file is editable.  

Basic Workflow

The Basic Workflow is ideal for the average user to setup a single shot without setting up any Real-World Alignment and saving the move to the SD Card. Moves that are saved in this manner will require the user to setup a Real-World Alignment upon reloading the move using either the Start or End Frame of the move. 

Pro Workflow

The Pro Workflow is more useful in the scenarios that multiple shots are going to be setup and saved to the SD Card in the same location. In this scenario a user will setup their Real-World Alignment before creating Shots using a Home Reference. After this Reference is setup once, several different shots can be created and saved. Similarly, when loading moves from the SD Card if multiple moves use the same Home Reference the Real-World Alignment step will only need to be completed once to load and play all the moves that use this shared reference point. If a user forgets to complete the Real-World Alignment step before loading a move that had previously been saved using a Home Reference, the user will be prompted that a Home Reference is needed. 

Tip and Tricks and Lessons you will learn:

A lot of time and care should be spent setting up these real world references (RWA). A few notes:

1. Pan Tilt accuracy - If you are off by a half of a degree your shot is busted. Really focus on getting your alignment right by using your EVF on your camera with zoom setting.  Try to find that real-world pixel that you can reliably align to.  Even the small amount of backlash that the spectrum has matters - more on that later.
2. Position accuracy - If you are high or low or left or right by an inch or so - it might not matter for your shot if your subject matter is all far from the camera. If your subject matter is close to the lens - it matters a whole lot more.  Think about what an inch off left would look like if you are 1 foot away from a vertical fence post.  Even if the rest of your shot is aligned by pan and tilt, your that fence post will be in a significantly different place and your passes won't blend well. Start off without near field objects for a safer shot until you are sure you can get your positions perfect each time.