The Image Labeler, Video Labeler, and Ground
Truth Labeler (requires Automated
Driving Toolbox™) apps enable you to label images, videos, and other ground truth data sources. You
can then export the labeled ground truth as a groundTruth
object. This object contains information about the:
Data source
Label definitions
Marked ground truth labels
You can share this object with:
Other labeling colleagues, who can use it to continue labeling
Algorithm developers, who can use it to train algorithms, such as an object detector or semantic segmentation network
Validation engineers, who can use it to validate algorithms
To export and share labeled ground truth data from one of the labeling apps, select Export Labels > To File. Then either share the exported MAT-file directly with individuals on your team or place it in a shared network location.
If the exported ground truth contains pixel labels, the app also generates a
PixelLabelData
folder containing the pixel label data. The
LabelData
table stored in the groundTruth
object
references the path to this folder. Share this folder along with the
groundTruth
object.
The labeling apps also enable you to save a MAT-file of the entire app session. Do not share this file. This file contains app preferences that are specific to your local machine, and it might not work on other machines.
If you re-export a ground truth object containing pixel label data, the app generates a
new PixelLabelData
folder. Even if you are overwriting the original
groundTruth
object, the app generates a new
PixelLabelData
folder. The generated folders are named
PixelLabelData_1
, PixelLabelData_2
, and so on,
depending on how many times you re-export the groundTruth
object to the
same folder.
When sharing a groundTruth
object, be sure to share the correct
PixelLabelData
folder associated with it. For example, if you overwrite
the original groundTruth
object, share the overwritten object and the newly
created PixelLabelData_1
folder.
In addition to sharing the groundTruth
object, you must also share the
data source, and any additional files associated with that data source.
App | Data Source | Files to Share |
---|---|---|
Image Labeler | Image collection |
|
Video Labeler or Ground Truth Labeler | Video |
|
Image sequence |
| |
Custom data source reader |
|
In the exported groundTruth
object, the
DataSource
property contains the absolute paths to the data source
files. For
example:
gTruth.DataSource
ans = groundTruthDataSource for an image collection with properties Source: { ' ...\matlab\toolbox\vision\visiondata\imageSets\cups\bigMug.jpg'; ' ...\matlab\toolbox\vision\visiondata\imageSets\cups\blueCup.jpg'; ' ...\matlab\toolbox\vision\visiondata\imageSets\cups\handMade.jpg' ... and 9 more }
groundTruth
object to a new location, you might need to change
the file paths stored in the groundTruthDataSource
object. Even if the data
source files are on a shared network, if other people map a different drive letter to their
network folder, the file paths can be incorrect.To update these paths, use the changeFilePaths
function. Specify the groundTruth
object as an input argument to this
function. Also specify a cell array of string vectors containing the old paths and new paths.
For example: {["C:\Shared\ImgFolder\Img1.png" "D:\Shared\ImgFolder\Img1.png"];
["C:\Shared\ImgFolder\Img2.png" "D:\Shared\ImgFolder\Img2.png"]; ...}
.
If your groundTruth
object contains pixel label data, the
changeFilePaths
function also updates the path names to the pixel data
stored in the PixelLabelData
folder.
Store the groundTruth
object in a location that is on the
MATLAB® search path. For more details, see What Is the MATLAB Search Path? (MATLAB).
For a video, an image sequence, or an image collection containing images from a single
folder, consider storing the groundTruth
object in the parent folder of the
data source. For image collections containing images from different folders, no specific
recommendations exist for where to store the object. You can label image collections using the
Image Labeler
only.