We are pleased to announce the release of a new version of our popular EMSE Locator software module. Locator 2.0 extends the tradition of easy-to-use software established by the original Locator and adds a host of new features.
The purpose of Locator is to facilitate the co-registration and integration of electroencephalography (EEG, scalp-measured brain electrical activity) with structural and functional information from MRI, CT, SPECT, and other imaging modalities that are more inherently tied to the brain structure and anatomy. Locator permits the user to precisely measure the locations at which brain electrical signals are measured so that the sources of the signals can be modeled using a realistic head model that accounts for head shape, tissue thicknesses and differing conductivities of skin, bone, brain, and cerebrospinal fluid.
Key Features and Capabilities of Locator
Locator is designed for EEG researchers who require precise electrode digitization, head shape acquisition, and integration with MRI or CT data for advanced analysis and modeling. With Locator, you can:
- Digitize electrode positions and head shape with real-time 3D visual feedback.
- Acquire head shape points and generate a wireframe model of the head surface for accurate anatomical representation.
- Define a head-based coordinate system by specifying three fiducial points (Nasion, LPA, RPA) to establish a spatial reference frame.
- Assess digitization accuracy using automatic error detection and Target Registration Error (TRE) reports, with visual overlays highlighting electrode alignment quality.
- Map digitized probes onto a standardized head (e.g., New York Head) to create template probes for guided digitization and group studies.
- Align electrodes with MRI or CT segmentation outputs for EEG-MRI co-registration and integrated modeling workflows.
- Apply geometric transformations to MRI-derived layers (e.g., scalp, skull, CSF, cortex) to unify anatomical surfaces in a single coordinate frame.
- Merge left and right cortical meshes (pial surfaces) to generate closed cortical surfaces suitable for BEM/FEM modeling.
- Crop photogrammetry-based 3D scans using an interactive bounding box to isolate the head and electrodes from background geometry.
- Export digitization results in multiple formats, including EMSE, EEGLAB, CTF, 4D, BESA, Curry, and Brain Imaging Data Structure (BIDS) for standardized data sharing.
- Generate 2D electrode placement based on any cap layouts for use in guided 3D probe digitization.
- Visualize digitized electrodes, fiducials, and head shapes in an interactive 3D environment, supporting rotation, zoom, and viewpoint control.
- View and export (x, y, z) coordinates of fiducials, electrodes, and head shape points in ASCII or neuroimaging-compatible formats.
Prepare integrated anatomical and electrode datasets for use in BEM/FEM modeling and advanced EEG analysis pipelines.
Tutorial Videos
Brief tutorial videos for Locator 2.0 can be found in this playlist.
