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Found 8 results

  1. Dear All, Thank you for taking the time to read this. I am attempting to create RTI's for my masters thesis, and am coming across the same error messages regardless of what I do. Both HSH and PTM have the same error messages (With the name swapped per method) that pop up in sequence 1 through to 3. I've attached images of the error pop-ups. I have created both HSH and PTM on this PC without issue before, and not moved where either of the fitters are, or the files used, but for some reason I can no longer create RTI. I am running a Windows 10 64bit OS, with AMD Ryzen 7 2700X Processor and 16GB RAM. I've checked the file pathways and dont see any spaces or things to cause issue - but have copied the file pathways below: L:\Diss_Images\A_Relief_RTI_img (There is then the jpeg-exports folder within) C:\RTIbuilder_v2_0_2 C:\RTIbuilder_v2_0_2\Fitters (Both PTM and HSH fitters are stored here.) If there's any more information I can provide that would help diagnose this issue please ask. Thanks in advance, Luke
  2. After the coefficients are found for Hemispherical Harmonics, how does RTIBuilder determine the direction of the surface normal? Does the program assume the surface is diffuse and look for the maximal lighting direction? I have seen multiple articles (Manfredi et. al.) that state that HSH more precisely determines surface normal direction, but neither those articles nor their references seem to point to how the surface normals are actually calculated. Unlike PTM, there are potentially multiple places where the gradient could be zero and with 16 coefficients, those locations are not easily solved for. Thanks for any assistance!
  3. Dear all I'm trying to create a 3th order HSH (16 variables) with RTIBuilder on my Mac. But every time when I execute the program I get a RTI file from the second order (9 variables) or even from the first order (4 variables), although the order is set on "3". Does anyone have an idea how I can solve this? Thanks in advance!
  4. Hi all, I have been trying to process a model with the HSH filter today - all the steps work up until the final execute stage. On pressing execute I get the following errors: No LD Information LP files has 0 images Please verify file paths Error encountered writing string to execute HSH fitter I can;t seem to figure out what any of these mean - I have followed the guide to the letter. I have double and triple checked that the files are in folders without spaces ( C:\Users\Sian\Pictures\100mm_Session_3\projectFolder\jpeg-exports) Please can anyone advise? Best, Sian
  5. Hello everybody, I'm new on this forum. I'm student in master's degree of photography in France. I'm actually doing my master's thesis and my subject deals with light calibration procedure for RTI acquisition with dome. To further develop my project, I need to analyse and potentially to modify PTM or/and HSH Fitter. I've ever downloaded the RTI builder and RTI viewer source code but the fitters aren't include with. Before implementing a solution myself i would know if some source code for fitters are available somewhere in any langage ? I've also discovered a new model for reflectance interpolation in a french thesis in metrology : https://tel.archives-ouvertes.fr/tel-01357821/documentthis model is called Discrete Modal Decomposition (DMD). Somebody have ever heard speaking of this modele before or of others models than those used in traditional RTI Builder (Ptm, SH, HSH) ? Thanks in advance for your answer and thanks to the Chi's team for the work they provide, this website and the forum is a gold mine for student and people interested in computational imaging for the cultural heritage domain, like me. Aurélien Vila
  6. Hi all, Has anyone encountered the following error when processing an HSH? "Problem with crop dimensions. Verify the crop area to continue." (see attached screen shot) The data fit just fine when I fit without cropping, but when trying again to process a cropped version, the same error came up. I also tried changing the cropped area, deselecting and re-selecting, but no luck. Any ideas what the problem might be? I have checked the usual suspects (spaces in file name, upper and lower case, umlauts, etc.). I am processing to and from an external hard drive due to the lack of space on my work computer and had just completed a successful HSH fit prior to this new data set that produced the error. Thanks for any pointers - Kathryn
  7. Can you comment on the strengths of each of the fitters (PTM or HSH)? The hope is to have a better idea of when to use each. Thank you, Jason
  8. Carla, Mark, Marlin and Community – I’ve some questions about reflective spheres and optimal normal reflection vector precision (that is the repeatability) and accuracy (how closely measured normal reflection vector values are to the actual value). The CHI “Guide to Highlight Image Capture, 2.0 (http://culturalheritageimaging.org/What_We_Offer/Downloads/RTI_Hlt_Capture_Guide_v2_0.pdf) explains that: “Depending on the size and portability of the target object, you must compose the camera’s field of view so it can encompass both the object and two reflecting spheres of an appropriate size. The spheres should have a diameter of at least 250 pixels in the resulting photograph.” (Pg. 3, Target Object with Reflective Spheres.) THE SET-UP- As a practical example, let’s say I’m capturing a 36” wide x 24” high painting using a 50mm lens. With space on either side of the frame for the spheres to be mounted so that they do not cast a shadow onto the canvas during 15° flash positions, the total width of the frame area is roughly 45”. With my 5D Mark II and a 50mm lens, shooting the captures in RAW, I get photos with a total frame size of 5616 horizontal pixels x 3744 vertical pixels, a 21.026 megapixel file (21.0MP). That equates to roughly 125 pixels per inch on the canvas. Let’s assume that when I manufacture the assembly jpg’s, I first distortion correct for the aberrations around the outer areas of the lens frame so that every pixel is metrological. A one inch reflective sphere is 125 pixels in this set-up – HALF the recommended pixel diameter. In my experience, really takes about 20 pixels, MINIMUM, to resolve a condition I am interested in documenting so that I may track its changes accurately. So in reality the smallest features that will resolve clearly in this composition are about an 1/8th of an inch diameter, about 3.2 mm. Let’s assume from a qualitative standpoint, I’m happy with that resolution. THE QUESTIONS- Normal reflection vectors taken from HSH assembly code calculate the normal reflection data using the brightest-to darkest RGBL values where the light source is the inverse of the highlight position on the spherical surface. To what degree am I decreasing both the accuracy and the precision extra variability or noise into the processing of normal reflection vectors by having a reflective sphere only HALF the recommended size? ​ Do the HSH algorithms require a nearly 250 pixel diameter hemisphere to accurately calculate the light sources and inverted reflection vectors? How much does variability (precision) depend upon having a minimum 250 pixel hemisphere? My guess is that the 250 pixel recommendation is based upon some optimization tests. But if nobody knows, perhaps I should gather that data? Thanks – Dale Kronkright (GOKConservator), Head of Conservation, Georgia O’Keeffe Museum
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