Collecting and Using GCPs with PIX4Dcatch and the Emlid Scanning Kit

This technical guide demonstrates how to collect and leverage Ground Control Points (GCPs) inside the PIX4Dcatch workflow. Using the combined power of PIX4D software and the hardware-optimized Emlid Scanning Kit, you can ensure sub-centimeter geospatial alignment. Additionally, we cover essential field methodologies for cleanly mapping architectural structures and vertical building facades.

GCP Survey Configuration

Incorporating geometric anchors into your mobile 3D data requires setting up localized points before initiating scans. This sequence is critically important if you plan to pass datasets to Pix4Dcloud systems for fully hands-off processing. Start the data setup by following these configuration steps:

• Navigate to the native **Survey** module dashboard area in the application interface.
• Tap **New Collection**, specify your unique file name string, and set the appropriate geometric target coordinate reference system.
• Thread your Emlid Reach RX cleanly onto a standard terrestrial survey rod.
• Plumb the hardware assembly precisely over your physical ground target marker center and tap **New Point**.
• Provide descriptive labels, define your explicit rover rod observation height, add structural reference photos if required, and establish your localized epoch averaging calculation times.

Select **Measure** to kick off the receiver. Once the position calculation time finishes averaging, the application automatically maps the precise survey-grade coordinates for your initial GCP control anchor. Repeat this explicit process across your remaining field targets.

Field Capturing Best Practices

Once your complete array of coordinate parameters is successfully logged, prepare your mobile apparatus to initiate scan recordings. Enter the app workspace and choose **Capture**, then open the diagnostic **Tools menu** icon positioned at the bottom right viewport corner. Tap directly on **Tag Detection** and select **Import Point Collection**—linking your recent survey project coordinates to automatically activate intelligent site auto-tags.

Re-mount the Emlid Reach RX and your mobile phone securely back onto the physical Emlid Scanning Kit handle assembly. If mapping a structural facade or high vertical surface wall, insert your survey rod directly into the threaded base slot located at the bottom of the handle grip framework. This hardware extension enables cleaner field paths for elevated vertical masonry features.

For top-tier model construction results, utilize a structured two-tiered pass framework along the building face:

• Low Pass Track: Execute a uniform, low-altitude sweep, maintaining a steady forward walking speed and fixed parallel distance offset from the exterior face.
• High Pass Track: Return along the target path with your rod extended upward, smoothly mapping higher building features with a stable vertical field perspective.

Ensure that both structural GCP markers feature prominently within the camera lens path during your capture passes. Registering these markers locks your mobile terrestrial data securely into place, allowing for flawless spatial merging with independent aerial drone photogrammetry maps.

Processing & Exports

With data collection complete, click stop to lock down your dataset file structures. High-accuracy mobile terrain scans can be immediately exported from your mobile device through two distinct workflows. You can package and transfer data bundles locally into professional desktop environments like **Pix4Dmatic**, or upload datasets straight to Pix4Dcloud infrastructure for automatic spatial compilation and model rendering.