Tie Point Creator Tutorial - ngageoint/voxel-globe GitHub Wiki
Once you have ingested control point and images, you are able to create tie points. A tie point is the 2D pixel location in a specific image that is associated with a 3D control point. We create these points using the "Tie Point Creator" app.
Start by loading an image set, Providence. Next, click the icon to list all available control points. Select the check boxes to enable the controls you plan on using.
images/tiepoint_creator_select2.png
Notice in the Cesium Map, yellow and blue circles start appearing. Yellow objects represet the currently "Active Control Point", identified in the lower left corner where it says "Super_West_Corner". The active control point can be changed by clicking on a blue dot or blue ring. Also the "Active Control Point" drop down box in the lower left corner can be used to designate the active control point.
The "Select All" button will select all the control points, while "Clear All" will deselect them all. Clicking "Select Matching Points" will check the database for any previously made tie points for the current image, and select the corresponding control points. This can be useful for resuming where you left off.
Once you have all of your control points selected, click the icon again and you are ready to start creating tie points.
To create a new tie point, click the + button in the lower left corner of the image viewer. When you do this, you will see a blue circle under your mouse in the image viewer. While in this mode, you can still click and drag, and mouse wheel zoom in and zoom out without placing the tie point. When you are ready, click were you want your tie point to go, and a yellow ring will appear
If you have the Map displayed on the left, you will now see a new yellow ray casting from the camera through the 3D world. Similar to the white rays that cast the center of the camera, these yellow (and blue for inactive control points) cast the tie point in the world. Once the cameras are registered, you should see the rays intersect with the control point, as seen above. If you are creating tie points before georegistering a model, they will not intersect. But after georegistration, come back to the Tie Point Creator and load the control points, and the ray will intersect using the newly registered cameras. The Providence camera were already georegistered. See the no metadata case for unregistered cameras.
You can also click and drag a yellow ring to move it to a more correct location. Sometimes zoom-ing in makes it easier to place more accurately.
Multiple tie points can be seen being projected by multiple cameras. Note: one of the control points is not currently used.
