ひかり拓本

Hikari rubbing is a digital rubbing technology developed by the Nara National Research Institute for Cultural Properties. Only the shadows created by oblique light are photographed, and the shadows from various angles are combined to capture the carved characters and patterns.

Rubbing is a traditional method of pasting paper onto a stonework, etc., and adding ink to the surface to transfer letters and patterns. "Hikari Rubbing" is an app that uses a camera instead of paper and light and shadow instead of ink to capture characters and patterns carved into stone.

It takes about 10 seconds to create each image to be combined, and you can complete the shooting and creation in 5 to 10 minutes, so you can see the results immediately after shooting.

[Main functions]

① Creation of rubbed copy

・Take a picture with a camera and create a rubbed image

・Create a rubbed image using an image that has already been taken

② Rubbed copy history management

・Saving the rubbed image and the shooting date ・Date of rubbing creation ・Title

・Display on the GSI map using the GPS of the smartphone

[Simple manual for making rubbed copies]

Rubbing method 1 (camera shooting)

① Aim the smartphone at the shooting target and fix it on a tripod, etc.

② Start the app

③ Specify "shooting method" and "rubbing settings"

④ Shoot the first image (background image) without shadows

⑤ Shoot the second and subsequent images (oblique light image) while illuminating it obliquely

⑥ Start rubbing

⑦ Completion of rubbed copy

⑧ Check the finish

⑨ If the shadow is not enough, repeat ④ to ⑧ and add a shadow

⑩ If you get an unwanted shadow, go back one step and repeat ④ to ⑧

⑪ If there is no problem, enter the title and save

Rubbed copy creation method 2 (image selection)

① Start the app

② Select one image without shadows (background image)

③ Select multiple images with oblique light (oblique light images)

④ Specify rubbing settings

(Note) ② to ④ are in no particular order

⑤ Specify partial addition/partial deletion for each oblique light image (if necessary)

⑥ Start rubbing

[Notes on using the Hikari Rubbed App]

・Hikari rubbing is an image processing technology that extracts only shadows created by oblique light (oblique light). is not.

- When using this application, a separate light source such as a flashlight is required to create shadows.

・If you create a shadow with a flashlight, etc., and other strong light such as sunlight is shining, it is necessary to take measures such as blocking the light.

・The rubbed image created with this application does not accurately represent the 3D shape of the object to be photographed. Please check the condition of the target surface by yourself.

・The purpose of this application is to improve the visibility of inscriptions by extracting and synthesizing only the shadows created by oblique light, and it is not possible to restore lost character shapes.

・We plan to tackle unfinished tasks such as the above OCR function and character shape restoration in the future.

・This application can shoot with a Bluetooth remote control when shooting. It recognizes the volume button as the shutter button.

・A message that uses location information is also displayed, but it is intended to be used to embed location information in the rubbed image and display it on the map (Geographical Survey Institute map).

[If a problem occurs]

・It may take some time to start up the camera. In that case, restart the app once, or tap numbers such as 1 and 2 on the shooting screen to switch to another camera.