This is the input value to be converted.
Input Lower and Input Upper define the upper and lower limit for the input value.
Output Lower and Output Upper define the limits for the output value.
The purpose of the spline graph is to allow nonlinear remapping. There are many cases where you might want the Range Mapper node’s output to rise gradually at first and then rise sharply as the upper limit is approached. One such case is a bicep’s muscle, the bulge of which depends on how far the elbow is bent. Most of the bulging occurs as the elbow approaches full bend. Splines give you an easy way to simulate these nonlinear dependencies.
To create a point, click on the graph; to move an existing point, drag the point; to delete a point, drag the point out of the graph. The graph’s X‑axis represents the input value, the Y‑axis the output value.
You can influence the spline’s curvature using a Tension slider, which you access by clicking the triangle next to the graph. The strength of the Tension slider controls the interpolation between the spline’s points. With a high Tension setting, the spline curve passes through all its points. With a low setting, a soft curve is created and the points control only the approximate path of the curve (i.e. the curve will not necessarily pass through the points). This soft curve is similar to a B-Spline.
The position of a selected point is shown in the X and Y boxes. You can enter new values for the point if desired. As with the Tension slider, click the triangle next to the graph to access the X and Y boxes. You can choose a particular shape for the graph’s curve using the context menu; right‑click on the graph and choose the desired curve shape such as Linear, Cubic or Sin. Default Points defines the number of points used to create the curve shape.
A straight line from the bottom left to the top right of the graph represents linear behavior (the same result as disabling Use Graph). If you add a point to the middle of the line and drag it up or down, the remapping becomes non-linear. If you want the output to increase gradually with low to medium input values then rise sharply as the input approaches its upper limit (such as for the biceps muscle mentioned earlier), draw a curve (by adding points and dragging them), from left to right, that is shallow at first then rises sharply towards the top right corner of the graph.
See RangeMapper Node.