I like using Business Center to compare plan sheets; the ability to adjust the transparency and precisely align sheets with each other (and at real-world scale to take accurate measurements!) makes TBC one of the handiest tools for this purpose that I've found.
One thing that I find restrictive however is the limited range of display styles.
If I'm simply comparing two different sheets, it is usually sufficient to set them at different view priorities with transparency at 50%, and use Display Style=None. I can distinguish between elements on each sheet by noting that the colors on the background sheet are faded, since they are "behind" the foreground sheet.
If I'm comparing three sheets, distinguishing what is on what sheet becomes more complicated. I usually change Display Style=Bluelined for one of the images. Display Style=Inverted can also be suitable, depending on the content of the sheet.
But in some instances I'm comparing a multitude of different sheets. For example, I may overlay an architectural sheet over a structural sheet over a civil sheet, over a demolition sheet - etc. (and then maybe multiple revisions of each sheet) usually for the purpose of correlation. In this scenario the display options become limiting.
I think it could be useful to add two additional property fields to georeferenced images:
- Foreground Color
- Background Color
In practice, this should be like using Display Style=Bluelined, but with more color options besides blue. Maybe these additional color options would be made to appear only when Display Style=Desaturated is selected.
As an extra, maybe it would be possible to also add a "Color Blend Mode" field where we could select options like "Add", "Subtract" and "Multiply" for example. I'm not sure what implementation details would look like for this though and I know it could potentially be far more complicated than changing foreground/background colors (depending on how PNG rendering is currently implemented within TBC). This property would be most useful in that by setting a pair of pages to complementary foreground colors and configuring the appropriate blend mode, it would be possible to really make the graphical differences between the pages pop out; wherever the sheets match the resulting color would appear black while differences would stand out in the color of the page they belong to. A couple products I know that use this technique for comparing PDF sheets are ProCore and PDF Studio. I do however realize that PDF comparison is not a primary application for TBC so a reluctance to add a bulk of features in this area would be understandable.
The image below shows what the sheet comparison looks like in PDF Studio 2019 with the complementary color blending.