1. A method of mapping an inter-tidal area, comprising:
obtaining, over a period of time, image data comprising: a sequence of images of the inter-tidal area at a range of different stages of the tide, and the time at which each image was obtained;
determining an elevation of a location in each image, by correlating the changes in an image value over time at the location with tidal data comprising the elevation of the tide over the period of time, wherein the tidal data comprises the transitions, over the period of time, between wet and dry at each of a plurality of elevations.
2. The method of claim 1, wherein determining the elevation comprises determining a measure of change with respect to time for the location.
3. (canceled)
4. The method of claim 1, wherein the elevation is determined based on a similarity between the measure of change at the location and the transitions at each elevation.
5. The method of claim 4, further comprising determining a distribution of a measure of similarity with respect to the plurality of elevations, and selecting an elevation for the location that corresponds with a maximum measure of similarity.
6. The method of claim 2, wherein the measure of change corresponds with the square of the gradient of an image value with respect to time for the location.
7. The method of claim 1, further comprising identifying whether the location stays wet or dry over the period of time.
8. The method of claim 7, further comprising determining a measure of change with respect to time for the location, and identifying the location as staying dry over the period of time by determining that the measure of change at the location, over the period of time, is below a threshold level.
9. The method of claim 7, further comprising determining a measure of change with respect to time for the at least one location, and identifying a location as staying wet over the period of time by determining that the frequency of changes in the image are above a threshold frequency.
10. The method of claim 7, wherein the elevation is determined based on a similarity between the measure of change at the location and the transitions at each elevation, and wherein a location is determined as staying wet or dry when the similarity between the measure of change and the transitions for each and every elevation is below a threshold level.
11. The method of claim 1, further comprising curve fitting to provide continuous functions that are representative of at least one of:
an image value with respect to time, the measure of change with respect to time, and the measure of similarity with respect to elevation.
12. The method of claim 1, wherein the tidal data further comprises a tidal elevation record.
13. The method of claim 1, wherein the sequence of images comprise at least one of: radar images, infra-red images, hyper-spectral images, and visible light images.
14. The method of claim 1, wherein the location in each image location comprises a pixel or a plurality of adjacent pixels.
15. The method of claim 1, wherein the image value corresponds with an alpha value, a red value, a green value andor a blue value of a location in the image.
16. The method of claim 1, wherein the sequence of images is collected at regular time intervals.
17. The method of claim 16, wherein the time intervals are between 15 minutes and 3 hours.
18. The method of claim 1, wherein the period of time is at least one diurnal tidal period.
19. The method of claim 1, wherein the period of time corresponds with at least one fortnightly (Mf) tidal period.
20. An apparatus for mapping an inter-tidal area, comprising:
a computer, configured to process a sequence of images of the inter-tidal area, obtained over a period of time at a range of different stages of the tide and a time at which each image was obtained, recorded on a data storage device so as to:
create a measure of change with respect to time for an image location,
determine an elevation for the location, based on a similarity between the measure of change at the location and the transitions from wet to dry at each elevation recorded in tidal data, wherein the tidal data comprises transitions with respect to time between wet and dry at each elevation.
21. (canceled)
22. The apparatus of claim 20, further comprising an imaging device for recording the sequence of images of the intertidal area to the data storage device.
23. The apparatus of claim 22, wherein the imaging device comprises a radar.
24. A computer readable medium comprising software for mapping an inter-tidal area that, when loaded on a suitable computer, configures the computer to process a sequence of images of the inter-tidal area, obtained over a period of time at a range of different stages of the tide and a time at which each image was obtained, recorded on a data storage device so as to:
create a measure of change with respect to time for an image location, and
determine an elevation for the location, based on a similarity between the measure of change at each location and the transitions from wet to dry at each elevation recorded in tidal data, wherein the tidal data comprises transitions with respect to time between wet and dry at each elevation.
25. (canceled)
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A tripod head comprising:
a mounting which is tiltable and allows a filming apparatus to be mounted thereon;
a counterbalancing mechanism comprising a spring and being configured to generate a resilient force on the spring so as to counterbalance with a rotation moment generated when the filming apparatus to be mounted on the mounting tilts;
and a resilient force adjusting mechanism configured to accommodate a weight of the filming apparatus and impart a resilient force in advance on the spring of the counterbalancing mechanism, wherein
the resilient force adjusting mechanism includes a rotating operation part, a cam coupled in between the rotating operation part and the spring and configured to slide with a rotation of the rotating operation part, and a cam follower in contact with a cam surface of the cam, the cam follower being supported by the counterbalancing mechanism, and
the counterbalancing mechanism is configured in such a manner that a magnitude of the resilient force imparted on the spring varies depending on the position where the cam follower contacts the cam.
2. The tripod head according to claim 1, wherein the cam surface of the cam is a curved surface, and on the cam surface, an inclination of tangent lines drawn virtually on the curved surface from a reference position of contact with respect to the cam follower to a position corresponding to an end of a turn of the rotating operation part with respect to a sliding direction of the cam is gradually reduced.
3. The tripod head according to claim 1, wherein the rotating operation part, the cam and the spring are configured and arranged such that the rotation of the rotating operation part directly causes the cam to slide which, in turn, imparts the resilient force on the spring.
4. The tripod head according to claim 1, further comprising
a coupling portion; and
a projection disposed on the rotating operation part;
wherein the cam is fived to the coupling portion and the rotation of the rotating operation part rotates the projection within threads of the coupling portion which directly causes the cam to slide.
5. The tripod head according to claim 4, wherein the cam is a first cam fixed to a first side of the coupling portion, and a second cam is fived to a second side of the coupling portion.
6. The tripod head according to claim 1, wherein the cam is configured to slide linearly.
7. The tripod head according to claim 1, further comprising a guide pin configured to guide a linear sliding movement of the cam.