METHOD OF MEASURING THE INTERIOR VOLUME OF AN OBJECT

Abstract

The invention relates to a method of measuring the interior volume of an object, in which the object is contactlessly scanned using a computer tomographic scanner, the scanning results are used for an automatised construction of a three-dimensional model of the interior volume of the object, and the interior volume of the object is measured using computer processing of the obtained three-dimensional model. For an automatised creation of the three-dimensional model of the interior volume of the object, including an object with an open contour, and to prevent the occurrence of artefacts during measuring of an object, mainly a non-metallic one, according to the invention the interior volume of the object is filled with a filler before scanning, wherein the filler is a reusable filler and the radiodensity of the filler differs from the radiodensity of the object. Additionally the invention relates to the application of the inventive method for measuring the interior volume of shoes.

Claims

1. Method of measuring the interior volume of a non-metallic object comprising metallic elements, in which: the interior volume of the object is filled with a filler (2), wherein the filler (2) is a reusable filler, the object is contactlessly scanned using a computer tomographic scanner, the scanning results are used for an automatised construction of a three-dimensional model of the interior volume of the object, and the interior volume of the object is measured using computer processing of the obtained three-dimensional model, characterised in that the radiodensity of the filler (2) differs from the radiodensity of the object, wherein in order to avoid artefacts from metallic elements on the image of the object quartz sand is used as the filler (2).

2. Method according to claim 1, characterised in that modified quartz sand is used as the filler (2), wherein the modified quartz sand is a quartz sand with additional ingredients, which allows to fixate an initially given shape.

3. Method according to claim 1, characterised in that before filling the interior volume of the object with filler (2) the open contour of the interior volume of the object is limited by at least one plug (3), wherein the at least one plug (3) is adapted to hold the filler within the boundaries of the interior volume of the object, wherein elastic containers with quartz sand or with modified quartz sand are used as plugs (3).

4. Method according to claim 1, characterised in that the interior volume of the object is filled with a filler (2) using a vibrating table.

5. Application of the method according to claim 1 for measuring the interior volume of shoes.

Description

SHORT DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows the outline of the object to be measured,

[0023] FIG. 2 shows the object to be measured in longitudinal section,

[0024] FIG. 3 shows a collection of plastic goods having a complex interior shape, as an example of embodiment of the invention,

[0025] FIG. 4 shows the obtained digital images,

[0026] FIG. 5 shows the obtained three-dimensional digital models of the interior volume of the objects to be measured.

EMBODIMENT OF THE INVENTION

[0027] FIG. 1 shows a plastic branch pipe whose interior volume is subject to measurement. FIG. 2 shows the same branch pipe in longitudinal section. It is well visible that the branch pipe in longitudinal section has an exterior contour made of the material 1 of the branch pipe, while in the connection places of the branch pipe the contour of the interior volume of the branch pipe is open. To carry out the measurement of the interior volume of the branch pipe its open contour is limited by at least one plug 3, subsequently the interior volume of the branch pipe is filled with the filler 2, and the branch pipe is contactlessly scanned using a computer tomographic scanner. After the contactless scanning the filler is withdrawn from the interior volume without destroying the branch pipe, and the scanning results are used to construct a three-dimensional model of the branch pipe, on the basis of which the interior volume of the branch pipe is measured.

[0028] An example of the embodiment of the invention was also realised for measuring the interior volume of plastic goods of complex interior shape (FIG. 3).

[0029] Quartz sand was used as filler. The choice of filler material was based on the difference in the radiodensities of the plastic (from ?800 HU to +200 HU) and the quartz sand (from +500 HU to +2000 HU), which made it possible to unambiguously distinguish between the exterior three-dimensional models of the objects and the three-dimensional models of their interior volume when using a computer tomographic scanner.

[0030] The plastic objects selected for the experiments were filled with quartz sand using a vibrating table, which rendered it possible to prevent the occurrence of air entrapments in the places where the filler contacts the interior surface of the objects to be measured. When objects with an open contour of the interior volume (open volume) are measured, elastic containers with quartz sand are used as plugs. If necessary, a correctional forming of the surface in the open places was carried out by means of the elastic containers with modified sand.

[0031] After filling the objects with sand, scanning was carried out on a medical computer tomographic scanner from the company Toshiba (see http://medical.toshiba.com/products/ct/aquillon-one-family/scalable-technology.php). These installations allow to carry out a three-dimensional measurement of the interior volume with a very high resolution. Additionally they make it possible to measure several objects arranged on a tray of 1750 mm in length at once.

[0032] Scanning schedule on the Toshiba Aquilion 32 tomographic scanner: [0033] voltage: 120 kV (exactly), [0034] current: 50 mA increasing to 95 mA on the lying bottle, [0035] matrix: 512?512 (exactly), [0036] field of view (FOV): 37.6?37.6 cm (exactly), [0037] thickness of the scanning section: 5 mm (exactly), [0038] thickness of the reconstruction section: 1 mm (exactly).

[0039] Hounsfield scale figures: [0040] lying bottle: 530-750 HU (approximately) [0041] round standing bottle: 830-870 HU (approximately) [0042] oval-shaped container: 780-850 HU (approximately) [0043] round standing bottle with thread: 780-950 HU (approximately) [0044] oval standing bottle with thread: 800-940 HU (approximately) [0045] Aeroplane mould: 900-930 HU (approximately) [0046] Locomotive mould: 970-1020 HU (approximately) [0047] Lorry mould: 1000-1100 HU (approximately) [0048] Passenger car mould: 900-970 HU (approximately).

[0049] The scanning resulted in a compilation of computer files in DICOM format. Their subsequent processing renders three-dimensional digital models of the interior volume of the objects.

[0050] Also in the process of scanning objects with such a filling of the interior volumes a three-dimensional image of the object was obtained that lacks artefacts from metallic elements, constructively included in the objects as mushrooms, circle-type formations and the like. The lack of artefacts allows avoidance of manual correction of the models and offers the possibility to automatise the subsequent computer processing. To this end, the scanning results were fed into a software for work with three-dimensional objects adding density filters (more than 400 and less than 1400) and combining integral elements. As a result, complete three-dimensional digital models of the interior volume of the measured objects were obtained.

INDUSTRIAL APPLICABILITY

[0051] The inventive method can be widely applied in different fields of industry in which the exact measurement of the interior volume of an object without destruction of the object to be measured is critical.

[0052] The inventive method can mainly be applied in an automatised control of the dimensions of the interior volume of objects in manufacturing but also in the automatised measuring and control of the interior volume of shoes.