Edit CRS Transform
CRS Transforms define the relationship between named Coordinate Reference Systems. A CRS Transform is made up of a series of transform steps, which are applied in order.
On the CRS tab for the active project, Coordinate Reference Systems are shown as boxes, while transforms are connecting arcs. Hovering the mouse over the (i) circle shows a summary of the transform and allows the transform to be edited, deleted, and locked.
Clicking the pen icon opens the edit dialog:
The left panel shows the current transformation steps. Here you can:
- Add new steps by dragging from the list to the right.
- Edit the step parameters
- Reorder steps by drag and drop.
- Remove steps by dragging them out of the main panel, or selecting them and clicking the scissor or bin icons below.
The buttons below operate on selections of steps. From left to right, these are:
- Cut the selected transformation steps, placing them on the clipboard.
- Copy the selected transformation steps to the clipboard.
- Paste the contents of the clipboard (if it is a valid set of transformation steps), replacing any selected steps
- Paste the contents of the clipboard before the selected step
- Delete the selected steps
- Select all steps
- Deselect all steps
- Invert the selected transformation steps.
Paste raw values
If the clipboard contains numbers separated by other characters eg 1.3,2.5,8 or 1.3 2.5 8 then you may paste them into a selected step. The clipboard must contain the same number of items as there are input fields in the step. i.e. 16 for matrix, 3 for scale
Matrix transform steps
A matrix transform step is provided. This can be useful if other software (such as CloudCompare) provides the transformation output in matrix form.
Reveal4D considers coordinate vectors to be column vectors. Transformations are applied by pre-multiplying coordinate vectors by the transformation matrix. Consequently, the right column, top three elements represent translation.
Some matrix-based geometry systems use row vectors and post-multiplication, with translation on the bottom row of the transformation matrix; if you have a matrix in this form, transpose it for use in Reveal4D.
Inverting transformation steps
Transformation steps can be inverted by selecting them and clicking the invert button below. If a continuous set of steps is selected, each step is inverted and the order is reversed, producing an inversion of the overall effect.
Note that discontinuous selections cannot be inverted.