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Add metadata aspect ratio transformation #667

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c64c975
Analytics: Added aspect ratio transformation for metadata frame
cemond-genetec Nov 4, 2025
b0380d5
Simplify AspectRatioTransformation node and review doc
cemond-genetec Nov 5, 2025
0f6b15c
Fix xml tags
cemond-genetec Nov 5, 2025
b496827
Fix missing end section
cemond-genetec Nov 5, 2025
4ddddac
Indentation of aspect ratio transformation example
cemond-genetec Nov 6, 2025
6a2dce7
Fix aspect ratio transformation is final and simply the sentence
cemond-genetec Nov 12, 2025
7280587
Add clarification when and which aspect ratio transformation is required
cemond-genetec Nov 12, 2025
890ab22
Add clarification for the Scale calculation for the centered crop exa…
cemond-genetec Jan 23, 2026
c39dfa9
Add missing required ratio attribute in AspectRatioTransformation type
cemond-genetec Feb 13, 2026
33746e8
Move ratio attribute of AspectRatioTransformation out of the sequence
cemond-genetec Feb 19, 2026
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31 changes: 31 additions & 0 deletions doc/Analytics.xml
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Expand Up @@ -657,6 +657,37 @@
</tt:Frame>
]]></programlisting>
</section>
</section>
<section>
<title>Aspect Ratio Dependant Transformation</title>
<para>This section describes the transformation specific to a scene aspect ratio.</para>
<para>Same as the transformation node, this node is used to apply final geometric transformations to the scene elements when the device supports more than one aspect ratio. This node allows the client to choose which transformation to apply, matching the metadata aspect ratio to the rendered aspect ratio.</para>
<para>The aspect ratio transformation node can contain the following elements:</para>
<programlisting><![CDATA[<xs:complexType name="AspectRatioTransformation">
<xs:sequence>
<xs:attribute name="ratio" type="xs:float" use="required"/>
<xs:element name="Translate" type="Vector" minOccurs="0"/>
<xs:element name="Scale" type="Vector" minOccurs="0"/>
...
</xs:sequence>
</xs:complexType>
]]></programlisting>
<para>If the transformation is a centered crop on one axis, no Translate vector is needed and Scale vector is calculated with this formula.</para>
<para>For the rendered aspect ratios greater than the video source aspect ratio, fix ScaleX = 1 and compute ScaleY = RenderedAspectRatio / VideoSourceAspectRatio.</para>
<para>For the rendered aspect ratios less than the video source aspect ratio, fix ScaleY = 1 and compute ScaleX = VideoSourceAspectRatio / RenderedAspectRatio.</para>
<para>For example, the coordinates of the scene description are given in a frame coordinate system, where the lower-left corner has coordinates (0,0) and the upper-right corner coordinates (1920,1440). The video source aspect ratio is 4:3. The device supports resolutions 1920x1080 and 960x576 corresponding aspect ratio 16:9 = 1.77777778 and 5:3 = 1.66666667.</para>
<para>The frame node resembles the following code, where the scale is set to crop the image to other supported aspect ratios:</para>
<programlisting><![CDATA[<tt:Frame UtcTime="2008-10-10T12:24:57.321">
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@sujithhanwha sujithhanwha Dec 4, 2025 •
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It would be helpful to include an example here, since this scale differs from the normalization scale used in the transformation.

Ratio = ProfileResolutionWidth / ProfileResolutionHeight
Scale X = VideoSourceWidth / ProfileWidth
Scale Y = VideoSourceHeight / ProfileHeight

Currently this assumes a centered crop (equal offsets on top and bottom, right and left). If the crop offset is not equal, should we consider applying an optional Translate to reposition the cropped region correctly ?

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@cemond-genetec cemond-genetec Dec 4, 2025

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Yes, the Translate is optional, but needed if it is not a centered crop. Do you recommend having one Frame example for centered use-case and one whole Frame example for a non-centered crop ?
I think a device should not have both for a video source.

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@cemond-genetec cemond-genetec Dec 4, 2025 •
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For the Scale for the centered case, we concluded 2 simple formulas.
When Resolution aspect ratio is greater than video source aspect ratio,
ScaleX = 1 and ScaleY = ResolutionAspectRatio / VideoSourceAspectRatio.

When Resolution aspect ratio is greater than video source aspect ratio,
ScaleY = 1 and ScaleX = VideoSourceAspectRatio / ResolutionAspectRatio.

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@sujithhanwha sujithhanwha Dec 5, 2025

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@cemond-genetec,

Thanks for the clarification.

Request to add an example also for clarity, please check if this kind of example is ok ?

Aspect Ratio Based Scaling

  • If ProfileAspectRatio > VideoSourceAspectRatio → the profile is wider than the source

    • Fix ScaleX = 1
    • Compute ScaleY = ProfileAspectRatio / VideoSourceAspectRatio

  • If VideoSourceAspectRatio > ProfileAspectRatio → the source is wider than the profile

    • Fix ScaleY = 1
    • Compute ScaleX = VideoSourceAspectRatio / ProfileAspectRatio

Example

Suppose:

  • Video source = 1920×1080 → Aspect ratio = 1920 /1080 = 1.78
  • Profile resolution = 640×480 → Aspect ratio = 640/480 = 1.33

Since VideoSourceAspectRatio > ProfileAspectRatio:

  • Fix ScaleY = 1
  • Calculate:
    ScaleX = 1.78/1.33 = Appx 1.34

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@cemond-genetec cemond-genetec Jan 23, 2026

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I pushed an update with this idea.

<tt:AspectRatioTransformation ratio="1.66666667">
<tt:Scale x="1" y="1.25"/>
</tt:AspectRatioTransformation>
<tt:AspectRatioTransformation ratio="1.77777778>
<tt:Scale x="1" y="1.33333333"/>
</tt:AspectRatioTransformation>
...
</tt:Frame>
]]></programlisting>
<para>In every Frame, the device must add the nodes for at least the currently configured aspect ratios. The node for the video source aspect ratio should be omitted.</para>
</section>
<section>
<title>Scene Elements</title>
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9 changes: 9 additions & 0 deletions wsdl/ver10/schema/common.xsd
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Expand Up @@ -267,6 +267,15 @@ IN NO EVENT WILL THE CORPORATION OR ITS MEMBERS OR THEIR AFFILIATES BE LIABLE FO
<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> <!-- first Vendor then ONVIF -->
</xs:sequence>
</xs:complexType>
<xs:complexType name="AspectRatioTransformation">
<xs:sequence>
<xs:attribute name="ratio" type="xs:float" use="required"/>
<xs:element name="Translate" type="tt:Vector" minOccurs="0"/>
<xs:element name="Scale" type="tt:Vector" minOccurs="0"/>
<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute processContents="lax"/>
</xs:complexType>
<!--===============================-->
<!-- Location/Orientation Types -->
<!--===============================-->
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1 change: 1 addition & 0 deletions wsdl/ver10/schema/metadatastream.xsd
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Expand Up @@ -291,6 +291,7 @@ IN NO EVENT WILL THE CORPORATION OR ITS MEMBERS OR THEIR AFFILIATES BE LIABLE FO
<xs:element name="Extension" type="tt:FrameExtension" minOccurs="0"/>
<xs:element name="SceneImageRef" type="xs:anyURI" minOccurs="0"/>
<xs:element name="SceneImage" type="xs:base64Binary" minOccurs="0"/>
<xs:element name="AspectRatioTranformation" type="tt:AspectRatioTransformation" minOccurs="0"/>
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@sujithhanwha sujithhanwha Dec 4, 2025

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Suggest to add the same as optional element inside object also, to keep it consistent with "ObjectTrack" Event.

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@cemond-genetec cemond-genetec Dec 4, 2025 •
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I think you are referring to A.10 Object Track Aggregation.
I agree the same issue applies if the VMS needs to draw or compare the tt::Object data on a specific resolution.
However, I am not sure the best place to put AspectRatioTransformation. To me, Object data should only contain the position in the video source area.

<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> <!-- reserved for ONVIF -->
</xs:sequence>
<xs:attribute name="UtcTime" type="xs:dateTime" use="required"/>
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