Frequently Asked Questions

What is iWitness?

What 's the difference between iWitness and iWitnessPRO?


How is iWitness used?

What kind of objects can iWitness measure and 3D model?

What are the PC system requirements to run iWitness?


What monitor screen settings are required?

What type of camera can I use with iWitness?

How much time is required to create 3D models and measurements in iWitness?


What do I need to know in advance of using the iWitness software?


TECHNICAL QUESTIONS



USB dongle-related issues

One (or more) of the following should help resolve any issues:

- The latest USB dongle drivers are always available from here: http://www.keylok.com/support/downloads.aspx

- Read KEYLOK's F.A.Q. and support: http://www.keylok.com/support/faq.aspx


How can I tell if my camera is already in the iWitness Camera Database?


Can I temporarily change the cursor to the Entity Select (White Arrow) tool? Answer: Yes, you can, please review this 60Kb video; changetoarrow.wmv


How do I "unReference" a point without deleting it?


How do I "move" a point after it has been marked? Use the "E"


(Edit/Review) button in the tool bar. 123Kb video; movepoints.wmv


How do I "fix" my last placed Reference Mark, if I mark it in error?


If I inadvertently Reference mark two or more sets of images with different point numbers and want them all to be the same point number, how do I fix this?


Why is it that when I take my calibration pictures and import them into iWitness, two cameras are presented for my one camera that I used to take the images?


I calibrated my camera months ago, and I forgot how to add the calibration from one computer to another. Is there a tip sheet how to deal with this?


How do I add more than one camera calibration description to the camera database for a 'like' model digital camera used on multiple computers?


When images are imported into iWitness, a warning dialog box reads: "This camera is not in the database. Cameras details must be completed manually"?


The camera icon in iWitness appears as a cartoon camera. Is there a way to update the cartoon camera so that the cameras specific make\model is displayed when I import my images?


I can't seem to find the specific pixel height and width of my digital cameras Sensor Type. Is there a reference guide I can use to determine this?


When I use the "Export TXT" function from the 3D Points List, and open up the file, I see seven columns of numbers. What are these numbers?


What does the “Quality” and the “Angle” represent in the 3D Point List?


Is there a quick reference guide for the criteria regarding the "iWitness Project Status Summary"?


How come when I try to calibrate my camera, using the supplied target sheets, I can't get the Relative Orientation or Green Tick Marks after marking all of the 18 black dots?


Is there a way to map really small objects like blood spatter at a homicide scene, to sub millimeter accuracy?


When I open up the project .iwp the image thumbnails are pink. How do I fix this?


What CAD programs does iWitness and iWitnessPRO export to?


I'm running Vista 64 bit and when I first install iWitness (or iWitnessPRO) I get a warning message and it won't install. What do I do?


When I use iWitnessPRO with AutoCal codes for camera calibration, I'm getting all "yellow tick marks" and the process fails, what do I do?


Are there any example projects of interior crime scene mapping?


I can't get the small thumbnail "Image Pop Up Windows" to display in iWitness or iWitnessPRO when using Vista or Windows 7, while it works fine in XP. Is there a way to fix this issue in Vista or Windows 7?



TIP SHEETS, HELP VIDEO CLIPS and TUTORIAL MOVIES 


Is there a tip sheet I can refer to for basic steps of the iWitness software?


Is there a 'general' camera settings tip sheet for Day & Night use?


Is there a tip sheet for using iWitnessPRO?


Is there a tip sheet re: digital SLR camera settings for iWitnessPRO?


Is there a tip sheet for using XYRectify?


Is there a tip sheet for using Zaraf?


Is there a tip sheet for "proper" and "improper referencing" of Facet Form Polyline Marking in iWitness?


Is there a movie clip for Facet Form Polyline Marking in iWitness?


Is there a tipsheet for Linking Two Projects to the same coordinate reference frame in iWitness / iWitnessPRO?


Is there a tip sheet for Mapping a Street Intersection with iWitness?


Is there a tip sheet for Using Handheld GPS with iWitness?


Is there an easy to follow procedure for using the "3D Transformation to Control" feature within iWitness?


Is there a movie I can watch to learn how to best calibrate my camera with the Autocal placards?


Is there a movie I can watch to learn how to best calibrate my camera with the (traditional) "black dot" paper targets?


How do I setup different UNIQUE ID camera descriptions for my DSLR using different lens combinations or different focal lengths?




What is iWitness?

iWitness is a MS Windows™ based software program for measuring and modeling objects and scenes. iWitness uses the technology of close-range photogrammetry, where the three-dimensional coordinates (X,Y,Z) of feature points on an object photographed from two or more locations can be accurately determined by making two-dimensional measurements on digital images.


Designed for use by non-photogrammetrists, iWitness is a powerful yet easy-to-use tool. iWitness builds 3D models and measurements after a few easy clicks on the digital images imported into the program.


iWitness is the world leader in low-cost, close-range photogrammetry. It is unmatched in its abilities to solve easily and accurately for 3D image coordinates using consumer grade or fully metric digital cameras.


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Is there a "quick tip sheet" for using iWitnessPRO?

Yes, we've put together an iWitnessPRO Quick Reference Guide. However, we strongly recommend that you read the iWitnessPRO User Manaul too. After you install iWitnessPRO, the Users Manaul is located at C:\Program Files\iWitnessPRO\docs.


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Is there a "quick tip sheet" for using XYRectify?

Yes, we've put together an XYRectify Tip Sheet. However, we strongly recommend that you read the XYRectify User Manaul too. XYRectify is a separate planar rectification program packaged and sold with iWitnessPRO.


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How is iWitness used?

A few simple steps:


  1. Take pictures from different angles of the objects you desire to measure and 3D model, and then import the digital images into the iWitness program.
  2. Mark common features on the different images using the "one cursor Marking Tool." The points are cross-referenced automatically and the camera positions and orientations are computed in the program background, transparent to the operator.
  3. iWitness accurately solves for the 3D points, line data, polylines and photo texturing.

    You can view the 3D point data results in iWitness' advanced 3D graphics viewer, or 3D Point List, as well as export the results as a DXF file to CAD. The results also are available in Text and CSV Formats.

To learn more, please take the iWitness Tour.

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What type of objects can iWitness measure and 3D model?

iWitness is optimized for use by law enforcement agencies, specifically in traffic accident reconstruction and forensic measurement. iWitness' powerful data acquisition and rigorous photogrammetric processing create fast, comprehensive 3D measurements as well as a permanent visual record of the scene being recorded.


The value of iWitness is not, however, restricted to the law enforcement sector. As a full-featured, close-range photogrammetric software system, iWitness can be applied to 3D reconstruction tasks in architecture, archaeology, engineering and medicine. iWitness handles the most complex measurement tasks: there are no restrictions on the number of images and measurement points.

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What are the PC system requirements to run iWitness/iWitnessPRO?

What monitor screen settings are required?


iWitness /iWitnessPRO requires a personal computer with:

  • Pentium 4 processor (or higher), with 64-bit Microsoft® Windows® XP, or higher operating systems. NOTE: iWitness & iWitnessPRO will run on 32-bit Windows, but requires a special installer, please specify this in your order.
  • Minimum 2GB of RAM
  • 100MB of free hard disk
  • Means of capturing & importing digital images
  • USB port for dongle key
  • Mouse (preferably with scroll wheel)
  • Full Systems Administrator rights to install and run the program

iWitness requires the "Color Quality" in the "Display Properties Settings" set at the highest possible settings (typically 32 bit). To achieve this, select the Control Panel+Display to assure the setting is made correctly.


Depending on the computers graphic card, there is a chance of experiencing OpenGL Hardware Acceleration problems, for the first time, when importing images or in the 3D graphics view of iWitness. This is easily corrected by adjusting the settings on the Hardware Acceleration Slider in the Control Panel+Display+Settings+ Advanced+Troubleshoot (tab).


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What type of camera can I use?


iWitness works with any digital camera that reads the Exchangeable Image File Format (EXIF). Most digital cameras now use the EXIF format. The format is part of the DCF standard created by JEITA to encourage interoperability between imaging devices. For more information on EXIF reference the website http://www.exif.org.


We recommend a digital camera with at least 10 megapixel ccd resolution for use with iWitness. Remember, a higher camera pixel resolution creates more accurate photogrammetric results in iWitness.


iWitness also works with any film camera. However, it is important to realize the film negative or scanned film print must have square pixels. We recommend that ZARAF (a simple preprocessor utility tool) is used to assure the pixels are indeed square before importing the image into iWitness or iWitnessPRO.


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How can I tell if my camera is already in the iWitness Camera Database?

iWitness stores most digital camera make and models in its Global database, but not all of them, as digital cameras are updated almost weekly. The Global database is continuously updated with new cameras. One can download the latest Global Database by clicking on the Global Camera Database's "Auto Update Button" (assuming one has an Internet connection).


To access the Global database, click on the menu of: Edit | Camera database... | Global. If your camera is not in the Global database, please refer to PART C of the iWitness Users Manual. NOTE: we strongly recommend that one calibrate their camera before initial project use, regardless of whether the camera is present in the Global database.


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How long does it take to create 3D models and measurements in iWitness?


Speed and efficiency separate iWitness from its competitors. The program's fast point marking and automatic camera orientation methods make it a breeze to operate, even by non-photogrammetrists.


Using iWitness, a simple project can be modeled in as little as five minutes. Very complex scenes can take up to several hours. Generally, the time required depends on the number of images being processed and the number of 3D objects requiring measurement and modeling. In the examples premiered on this website, operators with a basic understanding of the iWitness program created each project in under two hours.


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What CAD Programs does iWitness and iWitnessPRO export to?

iWitness will export to most Computer-Aided Design (CAD) programs, i.e., AutoCAD, AutoSketch, Crash and Crime Zone (by CAD Zone), MapScenes, Visual Statement, and many others that read the DXF file format.


In addition to the DXF file format, iWitness and iWitnesPRO allow for its Texture Mapping (textured entities including 3D vertices, image points of the texture and the texture itself) can be exported in the Virtual Reality Modeling Language VRML format. The VRML file and textures are saved as JPEG files. The image files comprise rectified images of the entities. A VRML Viewer is required to view the exported model.


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What do I need to know in advance of using the iWitness software?
It's easy to use iWitness. All you need is a basic understanding of the MS Windows™ operating system. No formal photogrammetry training is necessary. Additional experience with CAD drawing programs or other optical metrology instruments (such as a total station theodolite or 3D laser) will benefit operators, but are not requisites to begin using iWitness. Importing digital images into iWitness is easy as well. In addition, the easy-to-follow documentation and tutorial project will help prepare you for your first project. If you're interested in a formal training workshop, contact DCS.


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Is there a quick reference guide or a 'tip sheet' available?

Yes, the tip sheet is compiled in a one page PDF form - click here to download it.


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Are there any special settings that are required on my PC to run iWitness?

TURN "USER ACCOUNT CONTROL" OFF
[Turn Off User Account Control]
iWitness requires the MS Control Panel's User Account Control, Turned Off.


SCREEN DISPLAY COLORS
[Control Panel + Display properties + Settings ]
iWitness requires the Display Colors set at 32bit. You can check this setting by selecting Control Panel+Display+Settings


HARDWARE ACCELERATION
[Control Panel + Display + Display Properties + Settings + Advanced + Troubleshooting]


Some video cards may require that the Hardware Acceleration Slider is adjusted for the images to load properly in the iWitness program. If you encounter graphics problems, adjust the slider bar “one notch to the left”, and then retry. The goal is to keep the Slider as far to the “right” for the best graphics performance.


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Why is it that when I take my calibration pictures and import them into iWitness, two cameras are presented for my one camera that I used to take the images?


In this instance, it is very likely that your camera images were recorded with Auto Rotate On. To use your digital images in iWitness, ensure that the Auto Rotate is set to Off.

Example of Digital Camera LCD

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Sharing Like Camera Model Calibrations On Multiple Computers (for iWitness V1.08 and higher version releases)


The process of adding a calibrated camera description to the iWitness Local Camera Database from the 'Host computer' to the 'Remote computer' can be accomplished with any project.iwp file, in which the camera calibration had already been performed. The camera must have a Unique ID assigned. In our example below, we are using the actual ‘calibration.iwp’ file to demonstrate the steps.


i) When first calibrating the camera on the Host computer, assign a Unique ID to the camera, in the Camera Parameters dialog box. Enter a specific camera name for the camera, (for example, you might enter the last 5 digits of the cameras serial number.)


ii) After you've calibrated the camera with the Unique ID on the Host computer, the iWitness Local Camera Database is automatically updated.

iii) Save the project as e.g. 12345.iwp, with the "iwp", specifying the file extension for the iWitness Project.

iv) Next, open the 12345.iwp file on the Remote computer, and iWitness will automatically update the Camera Database once you click Save. Your Camera Database on the Remote computer will now present the user with the option of using the database Default camera, or Unique ID named "12345". Repeating step iv) on all other computers, will update the Local Camera Database as applicable. Special Note make sure there is only one iwp project running when you do this task, i.e, there cannot be 2 or more projects open (or minimized) at the same time.

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When images are imported into iWitness, a warning dialog box reads: "This camera is not in the database. Cameras details must be completed manually"


The iWitness camera database is continuously updated with digital camera information.  However, there may be cases when your specific camera is not in the camera database, and a few simple actions are required before the camera can be calibrated. If the images were taken in JPEG format, there's a high probability that the images support the Exchangeable Image File (EXIF) header information. iWitness will read the EXIF header, thus we recommend the user takes their pictures in the highest resolution in JPEG format.


The iWitness User Manual, Part C, as well as Movie #2 on the iWitness CD Media provides an in-depth explanation of what actions are required when the images are EXIF, and also when they are not EXIF.  We have prepared a PDF file than explains the most typical situation (i.e., when the images are EXIF, and are not in the iWitness Local or Global Database).

Click here for an example PDF file, with picture illustrations (325kb).  


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The camera icon in iWitness appears as a “cartoon camera”. Is there a way to update the cartoon camera so that my cameras specific make\model is displayed when I import images?”


Yes. We have created a simple procedure for this, and it is noted in the below PDF file.


Click here for the procedure to revise the Cartoon Camera to actual Camera Make\Model (46kb).


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I can't seem to find the specific pixel height and width of my digital cameras Sensor Type. Is there a reference guide I can use to determine this?


Yes. We have compiled a list of the most common sensors in the below noted PDF reference guide. The reference guide also provides an example of how to use the sensor size in iWitness, prior to conducting the camera calibration.


Click here for the Sensor size and reference guide (43kb).

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When I use the "Export TXT" function in the 3D Points List, and open up the file, I see seven columns of numbers. What are these numbers?

  • The left most column is the Point Label.
  • The next 3 columns from the left are the X, Y and Z point coordinate values determined by iWitness.
  • The fourth to sixth columns list the positional standard errors of the point's X, Y & Z coordinates.
  • The seventh column to the far right is the "text string descriptor" that was created in the "Information for 3D Point Dialog". The Information for 3D Points Dialog is called upon when the "P" key is pushed and the cursor is placed over a Referenced point.

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What does the “Quality” and the “Angle” represent in the 3D Point List?

Quality is the RMS value of image coordinate residuals for a given point. It is an internal measure of the network consistency. The quality value is influenced by the camera type (and if calibrated), as well as the precision of the point marking/referencing. With a commercial grade digital camera that has been calibrated by iWitness, the quality value will typically be in the range of 0.1 to 1.5 when proper image-marking is achieved.  The lower the Quality number the better. It should be noted that estimates of Quality will likely appear artificially low when there are only two images and less than 8-12 referenced points. More representative quality estimates are obtained when the points are imaged from at least three camera positions (or 'sightings').


The Angle value is determined from the 'n' intersecting light rays to a point. The Angle is then defined by the maximum angle of intersection subtended by the pairs of two light rays that intersect at the point. It is desirable that the Angle value be higher than 20 degrees or so, and Angles of less than 10 degrees should be avoided where possible. iWitness will not allow a point to be referenced if its Angle value is less than 3 degrees.


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Is there a quick reference guide for the criteria regarding the "iWitness Project Status Summary"?


Yes. We have compiled some helpful text boxes adjacent the Project Status Summary dialog box for quick reference - PDF form.


Click here for the Project Status Summary Reference Guide (39kb).

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Possible problems achieving the "RO" or Green Tick Marks while accomplishing a camera calibration.


One issue might be the focal length of the camera is grossly in error. This is becomingly increasingly less of a concern as more cameras record the nominal focal length in the EXIF header of the jpeg images. iWitness initially looks in the local camera database for the appropriate focal length. If the camera is not found, it will then look for the focal length in the global camera database. Once it locates the camera, it reads the focal length from the EXIF header.


Only in the situation where no focal length is stored in the image file, will iWitness use the default value in the global camera database. This may or may not be sufficiently representative depending upon what zoom setting is adopted. If you are in doubt of the proper focal length, go through the simple procedure in Section C3.1 of the Users Manual to determine an initial value for the focal length. Your local camera database will be updated with the result of this procedure. Then, re-start the camera calibration; the estimated focal length value will now be used and the calibration process will be successful.


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Is there a way to use iWitness to measure really small objects, like blood spatter?


Yes. We have compiled a helpful tip sheet. It will require that you calibrate your camera for close-up photography.

Click here for the "close up measurement guide" for iWitness (295kb).


Click here for the "close up calibration target sheet" (11kb).


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When I open up the project .iwp, the image thumbnails are pink. How do I fix this?


When renaming a project iwp, or moving the project folder with its images to e.g., a CD or DVD, the directory path to ‘point’ and acquire the project images is temporarily disconnected. The image thumbnails will appear as pink rectangles. To ‘point’ the iwp to the directory with the images, simply right mouse click with the cursor over any of the pink thumbnails which sets the Image Path. Path to your working folder where you’ve stored your images. Click on the image ‘xxxxxx.jpg’ that’s presented in the “Open” dialog box. Click the Open button Click “Yes” for “Set path for all images? Select the Save icon to save this new image path setting.


Click here for the "pink image thumbnail conversion guide" for iWitness (120kb PDF - (requires Acrobat Reader version 6 or higher).

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Is there an easy to follow procedure for using the "3D Transformation to Control" feature in iWitness?


We've created a very simple to follow process guide for using the 3D Transformation to Control using two networks stitched with four control points.


Cick here for the "3D transformation to control guide" for iWitness (632kb PDF.)

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Is there a tip sheet for using Zaraf?


We have created a movie to show the process steps of ZARAF using a scanned image from a 35mm format camera. In order to accurately measure scanned film negatives or scanned film prints in photogrammetry, the pixels must be square in format height and width. Zaraf is a software utility program that assures the pixels (rows and columns) are square. It is important to realize that "square pixels" are only part of the requirements for producing accurate photogrammetric XYZ coordinates. The focal length and lens distortion must also be solved; see iWitness' "FOOM" process.



I'm having problems installing when using Vista 64 bit, what should I do?


In iWitness V1.4.2 and iWitnessPRO 1.05 we updated drivers that address these installation issues. In the C:\Program Files\iWitness (or iWitnessPRO) click on the "DongleInstall.exe". This will update required drivers.

If you are using earlier versions of iWitness (or iWitnessPRO) we recommend you contact us for the latest versions.



When I use iWitnessPRO with AutoCal codes for camera calibration, I'm getting all "Yellow tick marks, not Green tickmarks, why is that"?


Section D of the User Manual covers the procedure. By default, iWitnessPRO is designed to automatically read red targets (only). You can select the pulldown menu for Edit + Project Settings and then click on the check mark for "Colour" Targets. Proceed to running the AutoCal.


Optionally you can open one of the calibration images and click the Q-key on the keyboard. With the Image-Scanning & Auto Measurement dialog now displayed, you might notice the AutoCal Red/Green dots are not fully filled (i.e., a target "blob".) To correct this, click the "Optimize" button (note: it might take 10 seconds to re-process the threshold.) Click here to see an example. The figure illustrated on the left is without using the Optimize, while the figure of the right illustrates the Optimize with proper target "blobs". You can now run the calibration process from the Pull Down Menu (Photogrammetry + AutoCal.)


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