Bitmap Region of Interest

Created from the Context menu for a Bitmap variable This crops a rectangular region from the bitmap. Useful to zoom in on a detail. The cropping region is in terms of coordinates and not pixels. If you know the coordinates you can specify them here, but typically you click on […]

Using FFTW with DTSource

FFTW (site) is a widely used software library to compute the Discrete Fourier Transform. The FFTW library is based on creating a data structure called a plan that is created based on the dimensions, if it is a forward or backward transform and the pointer for the input and output […]

Using Eigen with DTSource

How to use Eigen with DTSource. First download the Eigen distribution. Since this is a template library there is no source code to compile, just header files to include. However you need to make sure that Xcode will find the header files. Do that by going to the Build Settings, […]

Surface Intersection

An interesting example is computing implicit surfaces and intersecting them. Set up two surfaces, defined implicitly by -x^2 + y^2 + z = 0x^2 + y^2 + z = 2 First compute the two fields on a uniform grid. This is done through the Image Stack Computation followed by a […]

Image Stack Computation

Compute and modify channels in an image using expressions. There are two main ways to use this. One is to use the toolbar to create an image stack using expressions. You can compute multiple channels. For this you specify a grid using xmin,xmax,ymin,ymax,zmin,zmax and the grid size. The expression can […]

ImageTank vs DataGraph

A natural question is what is the relationship between ImageTank and DataGraph. Certainly DataGraph is older and more mature than ImageTank but ImageTank has some functions that can be found in DataGraph. This document is intended to compare the two programs and how the goals and design differ. ImageTank is […]

2D Region

This variable is a rectangular region in two dimensions. Determined by four numbers, xmin,xmax,ymin,ymax The most common way to create it is to use the Misc button in the toolbar. See this page for more information how to use it to change the region interactively. You can then use it […]