复选框和签名

复选框

使用复选框的多选字段可能有几种不同的类型。首先是互斥类型，然后是非互斥类型，在后者中可以选择多个选项。另一个重要方面是给定多选字段的可用选项数量。在某些情况下，可能只有一个选项，即复选框是否处于选中状态，而在其他情况下，可能有 10、20 或更多选项，以网格或表格的形式排列，就像许多体检表单一样。

您可以通过四种主要方式来为这些类型的多项选择字段添加标签。

为选项添加标签

Let's take an example to understand how you can label the options. Forms can include the options Project or Policy. In this case, you only have one field, and you only label the selected word, i.e. label the word Project if the checkbox next to it is checked or the word Policy if the checkbox next to it is checked. If neither is checked then you label neither, and both being checked is not possible, and such documents would just be deleted from the training set.

此方法的优点是您只有一个字段，需要的数据较少。它的另一个优点是不依赖于复选框的成功检测。如果复选框被检测为字母 X，则模型仍可以学习去识别这意味着它旁边的选项已被选中。

The disadvantage is that you need to make sure both options are roughly equally represented, which is not always the case. Potentially, in your training set, 90% of the documents might have Project checked. In this case, the model cannot perform well and this approach fails. The problem gets worse when you have more options because some of them are almost always rare. In these cases you may need to create fake documents with the rare options checked to balance things out.

为复选框添加标签，每个复选框使用单独的字段

In the above example, you may have one field called Project where you always label the checkbox for Project, and one field called policy where you always label the checkbox for Policy, whether they are checked or not. This has the advantage that the balance matters a lot less, even if one of the options is checked 90% of the time, the model still learns to recognize them because the checkboxes are always in the same place.

缺点是您有两个字段，而不是一个字段。当有两个选项时，这可能没什么问题，但是当使用 10 到 20 个字段而非一个字段时，添加标签会变得更加困难，并且模型更难训练，需要更多训练数据。

Another downside is that sometimes the checkbox might not be detected correctly and you may need to add more complex logic in the workflow to handle all the X, V or K returned characters. In some cases the OCR might even merge the checkbox with the word next to it, like XProject, requiring an even more complex RPA logic to handle this situation.

使用单个多值字段仅为复选框添加标签

多值字段是 Document Understanding 2022.10 版本的一部分。这样可以更轻松地添加标签，并且不受选中的不平衡选项的影响，而且在存在大量选项时也不会受到影响。但是，它仍然依赖于复选框检测的准确性，或者存在复选框可能与其旁边的选项合并的风险。OCR 错误很难防御。

使用单个多值字段为选项添加标签

这也使添加标签更容易，对复选框检测错误不那么敏感，但可能对不平衡的选项更敏感，就像第一个选项一样。

In our experience, all of these options may be appropriate in some situations. We initially preferred the first option, however, as the accuracy of the checkbox detection in UiPath Document OCR has improved, we have gravitated more towards option two and three. Options two and three also have another major advantage: they are compatible between Forms AI and our AI Center based ML packages. So you can start with Forms AI, and then if you find the accuracy is lower than expected, you can just move the dataset to a Document Manager session and just train an ML model directly without any other changes. This option has become particularly interesting as our ML packages have gotten more powerful and require less training data.

签名检测

Starting with the 2022.4 LTS Enterprise release, signatures can be detected using the UiPath Document OCR, hence, Machine Learning Models can directly detect signatures.

像在文档中为任何其他字段添加标签一样，为签名添加标签。只要被 UiPath 文档 OCR 检测到，机器学习模型就会学习将该字段识别为签名。

备注：

如需更深入的签名分析，您还可以使用签名比较模型（在 UiPath 图像分析 ML 包中）。