Problems with a Deck Project – Red X Photos

Table of Contents

Problem Overview

With the right layout of targets and good photo overlap, PhotoModeler will automatically detect the targets and orient all photos (i.e. solve the position and angle of the camera when each photo was taken). When the project solves, the target points become 3D points and the surface planes can then be defined, and deck panel tracing can begin.

But sometimes, one or more photos don’t orient - a red X appears on the photo thumbnail to indicate this. When a photo is not oriented, no data can be extracted from it.

The Red X on a photo problem is usually due to one or more of the following:

Not enough points.
Not enough point spread.
Not enough photo overlap.
A problem with the camera calibration.

Other tutorials and videos show how decking projects should be set up. We recommend starting there when learning boat deck measurement with PhotoModeler. See the Learning Boat Deck Measurement page for the learning resources.

In this document and the associated video, we will show how to recognize these types of problems by:

Assessing a project’s problem photos,
Assessing the target pattern/layout.

And then we can determine whether the project is:

Fixable with additional point marking and referencing, or coding of targets, or
Best split into separate projects, or
Started over with better target layout and/or more photos.

Follow along in the video to see why a couple photos didn't orient and how we determine what to do next.

Below is a description of a set of steps to assess a problem project. The time code for the relevant clip in the video is shown. Scroll to the time in the video above, or click to view the part of the video in a new browser tab.

Once the project is assessed, we can determine if it's possible to correct the problem!

Assessing the Project

Assess the project - the example project was processed and we have a couple Red X photos (unoriented):

Open each of the unoriented (red x) photos, select the points in the problem area, right click and choose Open Photos Showing Selected. 0:47
If points on the unoriented (red x) photos appear only on other unoriented photos (or if very few appear on oriented photos), they need more references on oriented photos 0:55
If the 3D Viewer shows a gap in the model, select points in the problem region, right click and in the menu choose Open Photos Showing Selected, for another way of assessing point coverage and photo overlap. 1:04

'Red X' photos.

Big gap in photo overlap.

Typical unoriented photos.

Note: PhotoModeler needs a minimum of six points in each photo (ideally 10-15 or more), with good spread across the photo, and these points need to be marked/detected on at least two photos (ideally three or more). See the Minimums Section in the online Help.

Possible reasons for a low point count:

Not enough targets were placed on the deck panel and fewer than the minimum were captured in the photo. 1:34
If the targets are too small (i.e. too far away from camera), or camera angle too low they may not be detectable. 1:42
Blurry photos - some targets couldn't be detected. 1:49
Obscured or Damaged Targets - boat rigging/components can obscure targets detected, or worn targets with visible damage to the dots or rings. 1:55
Lighting - shadows on or too close to target rings or glare can render targets undetectable. Sometimes targets can be reflected off shiny surfaces which can cause problems if detected. 2:04
Targets moved - if the targets moved accidentally while taking photos, PhotoModeler will have trouble reconciling the 3D location based on the changing position of the targets in photos. These weak points may be automatically un-coded/unreferenced by PhotoModeler. 2:18

Too few targets.

Targets too small and camera angle too low.

Targets are further apart in the 3rd image, it looks like one of them moved!

Shadows close to targets and rings or target damaged.

Other reasons photos may not orient:

Low point coverage, or points are linear or clustered in a small area of the photo: 2:35
Insufficient photo overlap in this part of the model, points could not be referenced on two photos (ideally three or more): 2:43
Occasionally projects will not fully orient due to a calibration issue. If there is good point coverage and good photo overlap and the project otherwise looks properly set up, the calibration may be to blame. 2:51

Low coverage, just a strip of targets.

Bad overlap between these sets of photos.

Correcting the Project

Is the project fixable?

In some projects, if there is photo overlap, but not enough targets visible, manually marking a few points on identifiable features, and referencing on other photo(s) can help with orientation. 3:09

Points marked on screws and referenced.

Point marked on one target, referenced to a coded target.

After adding the references, set unoriented photos' to 'Use and Adjust' by using right click on the thumbnail and set the 'Processing Action'. 3:30
Reprocess the project - check if the problem photos are now oriented. 3:40

Set the photo processing action - right click menu.

Occasionally, when a project is weak, running with Auto-calibration enabled (which runs by default if your project does not have a calibrated camera, or if chosen directly) will mean only a sub-set of the photos are used. Since the auto-calibration needs to solve not only the point and camera locations, but also the camera parameters (focal length, distortion, etc.) it needs a strong setup. A weak project will more likely have weak photos that are thrown out and unoriented. In this case, a work-around for the problem is to re-run the full photo set without auto-calibration, and instead, you preload the camera (in the new project wizard) from an auto-calibration result from a strong project (or use the result of the previous auto-calibration that only solved the good subset).

If a project seems like it meets all requirements, projects can be sent to PhotoModeler Tech Support for a review. Use the 'Send Files to Support' tool (click File, Help, Send Files...).

If all of the required photos can't be oriented, perhaps the project can be split into separate projects.

A project may be done best in separate sections, e.g. a swim platform, foredeck, or other distinct sections of the deck.

Remove the problem photos - right click on the image thumbnails and click Add/Remove Photos. 3:54
Start a new project with the set of removed photos. 4:08

A project for a distinct section of the deck - swim platform.

A separate project for the main cockpit area.

If there are too many issues, it may be most efficient to start the project over. Re-arrange and/or add targets, take a new set of photos and launch a new project.

In worst case scenario, the project needs to be restarted with a better layout of targets, and/or better photos. Adjust the positions of targets or add more if necessary, retake the photos. 4:27

Could have placed some targets here.

Look for regions of the deck where targets could be added, for better spread and target point count, even on areas that will not be modeled or measured. Adding targets in these areas will help with orientation as they will tie the sections of deck together. 4:34

Take photos from higher up and add some angled photos so that more of the deck is captured. This also helps tie various sections of the deck together. 4:44

Good overlap, with overview photos.

Considerations for Future Projects

Once you've diagnosed the problem, take note of where things went wrong. Make sure future projects have a good target layout with good spread. Also make sure photos have enough overlap and include some overview photos that help tie the scene together.

A good way to reduce orientation and other project problems, is to bring your laptop to the project site, load the photos and run the project. Seeing the initial result will help identify orientation problems before you remove targets and leave the marina. If need be, new photos (e.g. angled ones), can be taken to help cover longer sections of the deck to tie the model together. But remember, don't move targets around unless you're starting a new project.