Measuring upper tree diameters with a Mirror Relascope
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- เผยแพร่เมื่อ 31 ก.ค. 2024
- Lesson 6: An explanation on how to use a Mirror Relascope to measure tree diameters in different heights.
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#forestmensuration - วิทยาศาสตร์และเทคโนโลยี
Excellent demonstration. Will be helpful for younger generations of Biometricians. I met & studied with Dr.John Bell & Dr. Kim Illes at OSU Both John & Kim were close friends with Walter Bitterlich, the inventor of the Spiegel Relaskippy.
Thanks sir for your demonstration I'm a student of Department of Forestry and Range Management from Pakistan
Thank you for the presentation. please, I am interested in purchasing Criterion 1000, that instrument in yellow color, how do I get it for research purpose?
Is it required to measure the horizontal distance or to have a fix distance when measuring upper diameter? Thanks
There are two alternative approaches: 1) measuring distance and diameter to calculate the width that every Relaskope unit represents, or 2) using a fixed distance and use the known relation of 1:200 for every Relaskope unit. In a distance of 10m every narrow stripe represents 5cm (1:200 * 10m = 5 cm). My approach with measuring distance and width helps to use the full width of all scales, but is not a must. It can be an advantage to use a fixed distance of 10 or 15m, since you can then also measure the height of the position with the inbuilt scales at the same time.
Could you please advise if instead of Bitterlich relascope I can use TruePulse 360 for measuring D7 (diameter at 7 m height). There is the Missing Line mode in TruePulse that allows measuring horizontal distances between two points. Bitterlich relascope is more expensive compared to TruePulse 360. I would appreciate your opinion!
I would not recommend to use the missing distance mode for the measurement of upper diameters, because: 1) you would need a reflection from the edge of the stem, which is difficult, 2) I have no information about the precision of the inbuilt compass. The angle difference between left and right side of the stem is very small (depending on distance) and has a huge effect on the calculated distance. With a tachymeter or total Station I think it should work, but with the inbuilt electronic compass, I have my doubts. However, we never tried or compared this to other measurements. Interesting question!
@@forestinventory Thank you again for the advice! I would opt for Bitterlich relascope then. Please continue with videos!
Is the volume 1.86 cubic meter?
Yes, this is correct! First calculate the cross sectional areas as Pi/4*d^2 at lower and upper end and derive the average and then multiply with length!
Can you use calipers with lasers to measure upper DBH?
In principle yes, but it is not very accurate. The problem is that you hardly see the laser points and since you get no reflection from the very edge of the stem, it is rather difficult. Laser calipers are good to measure the diameter of lying deadwood, since it lays on the ground and you can see the laser points much better.
what distance are you from the tree?
In this example I used no fix distance. I find the distance where the dbh covers exactly all 8 relascope units. But you can also use a fixed distance. The width of each relascope unit is 1:200 of the distance then.
I can't see the numbers on these glasses clearly. Do you know the reason why?
If you are working in conditions with a lot of backlight, you can adjust the sunshade to see the scales better.
Plz make more content ....
I calculated 1,87 m^3
1,87m^3
Yes 👍
Maybe i need to study english first... thank you so musch..!!
Sorry, we have no subtitles in your language yet ;-)