Following on from our previous post announcing PhoToPlan Release 7, here is a video showing the new unwrapping function introduced in the “Ultimate” version. Please contact us for more information.
We are pleased to announce that the latest version of kubit’s PhoToPlan software for AutoCAD is now available for download.
The new features include:
- Support of AutoCAD 2012 and Autodesk products based on AutoCAD 2012.
- New higher level product “PhoToPlan Ultimate”.
- Generation of Ortho Photos from orientated images. Included in the “Ultimate” variant only.
- Fit cylinder with just a few clicks in two orientated images. no need for marked points on the cylinder . Included in the “Pro” and “Ultimate” variants.
- “Flatten drawing“ – project geometry to a UCS. For delivering 2D drawings from 3D wireframe.
- “Unwrap Cylinder” – from at least one orientated image and points on the cylinder PhoToPlan will create a flat image of the surface of the cylinder. Included in the “Ultimate” variant only.
- Create UCS from the “Dual image Draw” commands. Once defined, facades may be digitised using only a single image and with fast commands for switching between parallel planes using images only, digitising of elevations has been significantly speeded up.
- Improvements to the image orientation workflow. Controlling the viewports and view is vital for fast modelling. Release 7 eases this with a number of new commands.
- Support for “Ribbons” in AutoCAD 2010 to 2012: an alternative for the classic menu and toolbars (actually takes less space than showing all toolbars)
Each of these new features will be examined in forthcoming posts.
Release 7 is provided free of charge to existing users on subscription but please remember to request your upgraded license before installation.
A free of charge trial may be downloaded here.
Once a year the kubit resellers from around the world gather at kubit’s Dresden offices to review and discuss developments in surveying software and new products for the next year. I have just returned from the 2011 conference and am really pleased to report that the future of kubit software looks really promising. Both PhoToPlan and PointCloud have some new really powerful and important new tools that will help extract more information from the PointCloud or Photograph quicker and easier.
There will be many posts in the coming weeks and months to detail these improvements but briefly;
PointCloud: (both Basic and Pro) now include Orthographic Image Generation – a quick and easy to use tool that is ideal for extracting plans and elevations for tracing. There is also a new focus on industry specific tools – the first of these is PointSense Plant. PointCloud also benefits from the improvements to the pointcloud engine in AutoCAD 2012.
PhoToPlan: In addition to many workflow improvements, the tool will also feature a new ortho image tool – generating Orthographic Photographs from the combination of geometry (or pointclouds) and orientated images.
Detailed announcements will be made soon.
Drainage problems with the pavement on the gun deck of Martello Tower 24 this tower required a full record of the historic paving prior to lifting for English Heritage.
This is a rectified montage of the gun deck pavement and firing step of a Martello tower. It was achieved by 4m PAP (Pole Aerial Photography) in a single day on site. The pavement level is a stitch of 9 images, the firing step 12. The images were rectified in PhoToPlan and then balanced and feathered in Photoshop.
Control for the rectification was by REDM to detail points collected in TheoLt:
In this plan I plotted the wall top from intersection in PhoToPlan 3D, orientated to the same control points from our reconaisance KAP imagery:
This tower is impressively armed with a mighty 24pdr; we had to wait until it was lifted before we could record the pavement condition in advance of works to stop the leaking, visit when it rains and you get wet!
Once the pole is set up and the rig hoisted it’s a case of working as quickly as possible to get even illumination across the whole photo block…and taking advantage of rare moments of excitement like the bit where we have to negotiate the flag pole.
For completeness the pavement survey was required to cover the firing step so the images are rectified again but this time to the firing step plane. The control points are snapped onto the joint lines from the TST survey by TheoLt. 12 images got me around the ring.
I had hoped there would be a deep enough chord of the circle covered in each shot to make use of the minimum number of points I measured to describe the jointing of the circumference rail support blocks, this turned out to be the case but more points would have been better, some of the projected images came out a bit stretched!
Next the central pivot column is rectified so that the final montage is presented to a consistent scale:
The pivot post is easy: 6 points and its done! Bringing the pieces together completes the cover:
The 3 planes are combined into one single orthographic projection, there was a great deal of fitting needed to get the coverage of the pavement right up to the base of the central pivot post from oblique imagery taken with the pole on the firing step.
Re-inserting the montage back into AutoCAD and checking by PhoToPlan rectification showed a 9mm average discrepancy between the montage and the control points.
This documentation project is a great example of what can be done with PhoToPlan, Photoshop, AutoCAD TheoLt and….
…a camera on a stick!…
So in 4 easy steps we got from ‘no cover’ to ‘ortho’ cover.
The following text is adapted from a paper presented by Peter Waldhäusl (University of Technology, Vienna, Austria) and Cliff Ogleby (Dept. of Geomatics, University of Melbourne, Australia), at the ISPRS Commission V Symposium “Close Range Techniques and Machine Vision” in Melbourne, Australia, 1994. Simple rules that are to be observed for photography with non-metric cameras have been written, tested and published at the CIPA Symposium in Sofia in 1988.
1 – THE 3 GEOMETRIC RULES
• Measure some long distances between well-defined points.
• Define a minimum of one vertical distance (either using plumb line or vertical features on the building) and one horizontal.
• Do this on all sides of the building for control.
• Ideally, establish a network of 3D co-ordinated targets or points.
1.2- WIDE AREA STEREO PHOTOCOVER
• Take a ‘ring’ of pictures around the subject with an overlap of greater than 50%.
• Take shots from a height about half way up the subject, if possible.
• Include the context or setting: ground line, skyline etc.
• At each corner of the subject take a photo covering the two adjacent sides.
• Include the roof, if possible.
• No image should lack overlap.
• Add orthogonal, full façade shots for an overview and rectification.
1.3- DETAIL STEREO PHOTOCOVER
Stereo-pairs should be taken:
• Normal case (base-distance-ratio 1:4 to 1: 15), and/or
• Convergent case (base-distance-ratio 1:10 to 1: 15).
• Avoid the divergent case.
• Add close-up square on stereo-pairs for detail and measure control distances for them or place a scale bar in the view. Check photography overlaps at least 60%.
• If in doubt, add more shots and measured distances for any potentially obscured areas.
• Make sure enough control (at least 4 points) is visible in the stereo image area and at least 9 control piubnts in the single image area.
2 – THE 3 CAMERA RULES
2.1 – CAMERA PROPERTIES
• Fixed optics if possible. No zooming! Fully zoom-out, or fix the focus using adhesive tape or avoid zoom optics altogether. Do not use shift optics. Disable auto-focus
• Fixed focus distance. Fix at infinity, or a mean distance using adhesive tape, but only use one distance for the ‘ring’-photography and one distance for close-ups.
• The image format frame of the camera must be sharply visible on the images and have good contrast.
• The true documents are the original negatives or digital ‘RAW’ equivalents. Use a camera with a highest quality format setting.
2.2 – CAMERA CALIBRATION
Use the best quality, highest resolution and largest format camera available:
• A wide-angle lens is better than narrow angle for all round photography. Very wide-angle lenses should be avoided.
• Medium format is better than small format.
• Calibrated cameras are better than not calibrated.
• Standard calibration information is needed for each camera/lens combination and each focus setting used.
• A standardised colour chart should be used.
2.3 – IMAGE EXPOSURE
Consistent exposure and coverage is required.
• Work with consistent illumination: beware deep dark shadows!
• Plan for the best time of day
• Use a tripod and cable release/remote control to get sharp images.
• Optimise shutter speed and aperture by using a ‘slow’ ISO setting ..
• Use RAW or ‘high quality’ or ‘fine’/’super fine’ setting on digital cameras.
• Test and check the exposure using the histogram to understand the balance needed.
3 – THE 3 PROCEDURAL RULES
3.1 – RECORD SITE, CONTROL & PHOTO LAYOUT
Make proper witnessing diagrams of:
• The ground plan with the direction of north indicated
• The elevations of each façade (1:100 – 1: 500 scale). Show the location of the measured control points.
• Photo locations and directions (with frame number).
• Single photo coverage and stereo coverage.
• Control point locations, distances and plumb-lines.
3.2 – LOG THE METADATA
Include the following:
• Site name, location and geo-reference, owner’s name and address.
• Date, weather and personnel. Client, commissioning body, artists, architects, permissions, obligations, etc.
• Cameras, optics, focus and distance settings.
• Calibration report, if available.
• Description of place, site, history, bibliography etc.
• Remember to document the process as you go.
3.3 – ARCHIVE
Data must be complete, stable, safe and accessible:
• Check completeness and correctness before leaving the site.
• Save images to a reliable site off the camera.
• Save RAW formats to convert into standard TIFFs. Remember a CD is not forever!
• Write down everything immediately.
• Don’t crop any of the images – use the full format.
• Ensure the original and copies of the control data, site diagrams and images are kept together at separate sites.
Although these rules were devised for ‘classical’ (stereo) phtogrammetic recording they hold true for photocover in general. The rules have been modified to suit digital camera work and have not incorporated the use of the Exif data in processing the images.
PhotoPlan3D= Simple photogrammetric plotting in AutoCAD!
PhoToPlan3D by kubit makes 2 useful aspects of photogrammetry available for AutoCAD users: 1st plotting from 2 (or more) images by intersection in 3D and 2nd plotting by projection from single images on to a plane. When used together the PhotoToPlan3D toolset enables the use of non metric imagery for surprisingly good results as a data source in AutoCAD.
Ther are 3 main aspects to getting the best out of PhoToPlan 3D: Control, Image condition and image orientation.
The first thing is to get a grip on is the relationship between the image and the control required to orient it. Let’s look at the control 1st.
The distribution of control points should be as wide as possible but should not rely on clusters in the centre of the area to be mapped. The number of control points is on the high side if you are used to using the minimum of 4 in PhoToPlan2D, the minimum of 9 points seems to be a bit tiresome but the benefits of the higher density of control will be worth it! If you imagine the task as filling a ‘data hole’ a good distribution of points would be not only around the edges of the hole but in the hole itself too! There are 3 basic rules on control points:
1. The more the merrier, 9 points per image is the minimum!
2. A wide distribution is better than not and
3. The closer to the data area the better
The condition of the imagery has a big effect on the precision achievable; this can be characterized in 4 elements:
1. The disposition of the images. If the images are captured from camera positions too close together or too far apart the intersection of rays between them and the object space will be either too obtuse or too accute, it helps to think in terms of a 90 to 60 degree intersection as ideal. If the stand-off from the camera to the subject has too great a variance the results will be poor. PhoToPlan3D will give you results from poorly conditioned imagery but the precision will proportionally poor too! Big X,Y rotations between images are not a problem although its helpful to resolve this at insert.
2. The convergence of the images. You will get nowhere if the images are not covering the subject area! Also if they point at the subject too obliquely you will find it hard to find common points between the images when plotting.
3. The consistency of the images. Ideally image pairs should be from the same camera and lens. It’s difficult (but not impossible) to achieve good intersections when one image is taken with a wide angle lens and the next with a telephoto.
4. Camera calibration information. If camera calibration data is available it should be used; PhoToPlan3D works with an ‘inverse’ calibration based on an assumed focal length, if the true focal length can be used the precision is better. Relying on the image EXIF data is not enough.
The quality of the image orientation depends on a combination of the image condition and the control quality. The image orientation panel is very flexible and it can be used to experiment with control point configurations point by point to see what gives the best result.
It’s worth noting that the constellation of control points used will change as new points are added, the precision (as reported by the standard deviation) may well decrease beyond a certain number of points and the reported worst case point will change: experimentation here pays off. The effect of adding new points can be to dilute the precision!
Tip if you are using imperial units in AutoCAD the ‘Deviation’ results will not be easy to read as the scores will be fractions of an inch. Set the AutoCAD units to decimal with at least 4 decimal places to see the scores!
Refining the image orientation The initial 9 points for the first image may be the only points you have but if you are working with a point cloud or existing 3D survey data its well worth adding more points and testing which configuration of points works best. Its simply a case of holding off hitting the ‘Create orientated image’ button until the standard deviation is as low as possible.
Let’s look at the orientation procedure in detail:
With the 2 images loaded on a convenient UCS and the control points marked the next step is to open the Image Orientation panel and begin to add control points to the orientation, this is done by point matching between the image and the control.
Tip: the deviation scores are not displayed until the destination image name has been set.
Note on precision: The standard deviation (SD) refers to the performance of the fit between the image and the control geometry. If the SD of two image orientations is 1cm each it can be expected that the resultant precision when plotting between then will be roughly double the SD i.e: 2cm per point.
The orientation will complete with the Create orientated image function and it is presented in CamNav view:This example is a good one to look at the registration across the image area. The control points are mostly in the centre and left side of the image, the fit is poor around the edges ( particularly at the apex of the pediment on the right). The distribution of control points could be better!
Reducing the plan rotation in the pair improves precision. By increasing the density of control points and choosing images with less tilt between them the precision is improved but the quality of the pair in terms of parallelism with the subject seems to have a big impact on the precision of digitised lines. Here I have loaded 2 images with more vertical displacement but less convergence :Despite the deep Z shift between them these two images have a better parallelism. The orientation SD was refined by selecting 18 points and deactivating the worst fit point and then adding new points (this worked better than juggling the relative fit of the 1st 18) the SDs came in at 10 and 9mm. Here are 2 pairs with different characteristics:
The relative plan rotation of the images seems to be more important then the tilt or depth displacement. Surprisingly in the 2 pairs above I got far better results with pair 1 than pair 2, pair 2 is a significantly convergent case whereas pair 1, despite the big Z shift and vertical tilt has better parallelism.
By repeating the image orienatation and testing lines (in blue in the screen shot) against the control point psositions I can gain confidence in the pair. Pair 2, despite comfortable SD scores (11 and 12mm), plots consitently dispalced by 2-3cm.
The difference in the performance of the 2 pairs can be explained by the planar orientation; the best pair were taken in parallel and worked well even though they have a big stand off variation.
It’s a good idea to experiment to find the best image condition. One of the great strengths of PhoToPlan 3D is the flexibilioy you have to try things out and see what the resukts are like before you commit to plotting. Having got the orientation refinement method practised and making sure there is an abundance of control and imagery available means the optimum image condition can be found. The classic 3X3 rules (contained in this pdf) still hold for photogrammetric capture but it seems that PhoToPlan3D works best with near ‘square on’ imagery!