Using PIX4Dcatch with your mobile device, it is possible to measure single points, also known as Ground Control Points (GCPs). Accurate GCPs increase the global accuracy of the project and can also be used as checkpoints for assessing the accuracy of the reconstruction.
IN THIS ARTICLE
Create a new Point Collection
Measure Points
Measure points using a survey pole/tripod
Measure points using viDoc downward laser
Import points
List points
Edit points
Reference photos
Delete points
Rename points
Manage Point Collections
List Point Collections
Export Point Collections
Delete Point Collections
How to import points to PIX4Dmatic
Create a new Point Collection
Before measuring points, it is necessary to create a new collection to store the measured points.
-
Tap the
icon from the main screen to open the Tools dialog.
-
Select
Point Management
- All point collections are stored and can be accessed here.
- Tap the New Collection
button to create a new point collection to store the measured points.
-
PIX4Dcatch Create Point Collection dialog.
- Name the new Point Collection.
- Select Point CRS(default).
- Select the desired output coordinate reference system.
-
Choose the horizontal coordinate reference system.
-
Choose the vertical coordinate reference system.
-
Select the geoid when available.
-
-
- Tap Save.
Measure Points
With a point collection, it is now possible to measure points. Two methods are available to measure these using PIX4Dcatch, with a survey pole/tripod or hand-held using the downward-facing laser on the viDoc RTK rover.
Measure points using a survey pole/tripod
- Create or select the desired Point Collection where the points will be saved.
- Tap the New Point
button.
- Point Name will be auto-generated based on the Point collection name, but it can be modified.
- Enter the vertical offset, optional details, and measurement duration:
PIX4Dcatch New Point dialog.
- Antenna Height / Altitude Correction. Enter the distance from the point to the base of the antenna of the viDoc RTK rover.
- Use Laser is toggled off.
- Enter:
- Description (Optional). A text description can be added when measuring the point.
- Reference Photos (Optional).
- Measurement Duration. (30 seconds recommended).
- Tap the Measure
button. It is recommended to wait for RTK Fixed and better HDOP values before measuring when achievable.
The measurement will begin once the bubble is aligned in the circle. The green bubble needs to remain in the center to start and continue the GCP measurement. The measurement will pause if the bubble drifts outside of the circle and will resume once realigned.
PIX4Dcatch measuring a new point.
All points measured will be saved and accessible in their Point Collection. Continue measuring new points following the same workflow. It is also possible to edit the name and/or description, add reference photos, and delete points. For more information: Edit points.
Measure points using viDoc downward laser
Toggling the Use Laser button allows the collection of GCPs using the downward-facing laser on the viDoc RTK rover.
- Create or select the desired Point Collection where the points will be saved.
- Tap on the New Point
button.
- Enter the optional details and measurement duration:
PIX4Dcatch New Point dialog with Use Laser toggled on.
- Antenna Height / Altitude Correction: This field should be blank.
- Toggle Use Laser on
- Enter:
- Description (Optional). A description can be added only when measuring the point.
- Reference Photos (Optional)
- Measurement Duration. (30 seconds recommended)
- Tap the Measure
button. It is recommended to wait for RTK Fixed and better HDOP values before measuring when achievable.
Aim the laser at the center of the control point to measure. The measurement will begin once the bubble is aligned in the circle. The green bubble needs to remain in the center to start and continue the GCP measurement. The measurement will pause if the bubble drifts outside of the circle and will resume once realigned.
PIC4Dcatch measuring a new point.
All points measured will be saved and accessible in their Point Collection. Continue measuring new points following the same workflow. It is also possible to edit the name and/or description, add reference photos, and delete points. For more information: Edit points.
Import points
PIX4Dcatch is also capable of importing GCP coordinates into an existing Collection. If the desired Collection does not exist yet, please create it first. Then there is an option to Import Points. Please note that coordinates have to be in the same coordinates system as the Collection itself. For input format, please refer here: Tie points (GCPs, CPs) import format - PIX4Dmatic
List points
Select a collection for the list of points measured.
PIX4Dcatch single point collection dialog.
-
Export Point collection. Complete(full information) and PIX4Dmatic-based files(for direct import to PIX4Dmatic) and logs are exported.
- Collection name
- The number of measured points currently in the collection.
-
Toggle list and map views
- Collected points.
-
PIX4Dcatch single point measurement dialog.
- Point name.
- RTK/GPS tag.
- Horizontal and vertical accuracies.
- Coordinates measured.
-
Date measured.
-
Measurement duration.
-
-
Measure a new Point.
- Output coordinate reference system for the Point collection.
Edit points
It is possible to add and edit reference photos, rename and delete points and point collections during and after the measurements.
Reference photos
PIX4Dcatch single-point reference photos
It is possible to attach reference photos to each point to aid identification. A reference photo can be taken before measuring a New Point or after the point has been measured and saved.
- There are two ways to access the reference photo camera.
- Before measuring the GCP, from the New GCP dialog, tap the Camera icon
in the Reference Photos (Optional) tab.
New GCP Reference Photos (Optional) tab
- After measuring the GCP in the list of saved GCPs, press and hold the desired single-point measurement and select Add photos
from the dropdown menu.
Long-press a saved single-point measurement to add reference photos
- Before measuring the GCP, from the New GCP dialog, tap the Camera icon
- Frame the point and tap
to capture a reference photo. Take multiple photos as needed. Delete unwanted photos by tapping the
icon.
Capturing a reference photo
- Tap
to accept and save the photos or
to cancel when finished.
Delete Points
It is possible to delete single points and whole collections as needed.
Delete Single Points
A single point can be deleted from a Point Collection.
PIX4Dcatch Delete point dialog
- Tap and hold the point to be deleted.
- From the menu, Tap Delete
.
- Confirm by tapping Delete
- Abort by tapping Delete
- Confirm by tapping Delete
Rename Points
It is possible to rename single points and whole collections as needed.
PIX4Dcatch edit Point Collection menu.
- Tap and hold the Point Collection or single-point to be renamed.
- From the menu, Tap Rename
.
- Enter the new name and select Rename.
Manage Point Collections
List Point Collections
PIX4Dcatch Point Management dialog.
From the Point Management dialog window, it is possible to:
- See the number of collections.
-
Toggle between list and map views.
- List of existing collections.
-
Input coordinate reference system.
-
The number of measured points in the collection.
-
-
Start a new Point collection.
Select a collection for the list of points measured.
Export Point Collections
Once points have been measured, they can be exported in predefined file formats.
PIX4Dcatch Point collection dialog.
1. Select the desired Point Collection from the Point Management dialog.
2. Tap Export at the top of the screen.
- Several files are generated:
Files exported from PIX4Dcatch of a GCP collection.
- Images folder: Contains the Reference image files.
- Records folder: Contains individual point .json files and logs (for internal use).
- project_name_Metadata.json file (for internal use).
- project_name-complete.csv: Generic point file with all information.
- project_name-PIX4Dmatic.csv: File that's compatible with direct import in PIX4Dmatic.
After the files are exported, they can be copied or shared and used in PIX4Dmatic or other third-party software.
Delete Point Collections
A Point Collection can be deleted from the Point Collection management screen.
PIX4Dcatch edit Point Collection menu.
- Tap and hold the Point Collection to be deleted.
- From the menu, Tap Delete
.
- Confirm by tapping Delete
.
- Abort by tapping Delete
- Confirm by tapping Delete
How to import points to PIX4Dmatic
With the exported project_name-PIX4Dmatic.csv it can now be imported directly into PIX4Dmatic.
Importing a GCP file into PIX4Dmatic.
To import the project_name-PIX4Dmatic.csv into PIX4Dmatic:
- Open project in PIX4Dmatic
- Click
Tie Points to open the Tie Points table.
- Drag and drop, or use the Select from disk option to specify the PIX4Dmatic.csv file with GCPs.
- Define the Horizontal and vertical coordinate reference system.
- (Optional) Define the Geoid or Geoid height.
- Click Apply.
After the points are imported, they are displayed in the Tie points table, the 2D and 3D view.
For more information: Tie Points (GCPs, MTPs, and CPs) in PIX4Dmatic.
Article feedback (for troubleshooting, post here instead)
0 comments