How much ground can I see?

[npalen]

If you ever intend to install the HDMI out board to use FPV goggles, the bit rate on the P3A will sorely disappoint. It's an unadvertised difference that bit a few P3A owners, after installing the HDMI board for goggle use. The P3P HDMI output is significantly better quality. Also, the still jpg images extracted from the 24 fps 4K video on the P3P are very usable at 4-7 MB each! You get 24 of them every second! Try that with the still camera capture! However, for dedicated still captures alone, there is no difference. The price difference is also less now than at original release, over a year ago. It's about $100-$200, instead of $279.

So using the HDMI output of a Nvidia Shield K1 from a P3A probably wouldn't be that great either for, say, a TV monitor?

 

[Tenly]

So using the HDMI output of a Nvidia Shield K1 from a P3A probably wouldn't be that great either for, say, a TV monitor?

No! That's not true at all! It will look great! I had a P3A before I upgraded to the P3P and I used to use a couple of different FPV headsets and the video was excellent. You'll have a few dropped frames here and there - and if you put it up right beside a P3P - you'll see what GadgetGuy meant by the P3P being "better", but I don't think he was trying to say the P3A is bad - especially to the point of being unusable!

Give it a try. I'm sure you'll find it more than adequate!

 

[GadgetGuy]

No! That's not true at all! It will look great! I had a P3A before I upgraded to the P3P and I used to use a couple of different FPV headsets and the video was excellent. You'll have a few dropped frames here and there - and if you put it up right beside a P3P - you'll see what GadgetGuy meant by the P3P being "better", but I don't think he was trying to say the P3A is bad - especially to the point of being unusable!

Give it a try. I'm sure you'll find it more than adequate!

I'll defer to Tenly, having never owned a P3A to compare, and only passing along what I have read here from those that do. Many P3A owners were upset that DJI didn't fully disclose all the differences between the P3P and the P3A. I'm sure the HDMI output is usable from the P3A, but it is far better from the P3P. If FPV quality from HDMI output is important, get the P3P. The difference is caused by the lower video bit rate from the camera P3A camera, which saved a few dollars in cost for DJI.

 

[Tenly]

I'll defer to Tenly, having never owned a P3A to compare, and only passing along what I have read here from those that do. Many P3A owners were upset that DJI didn't fully disclose all the differences between the P3P and the P3A. I'm sure the HDMI output is usable from the P3A, but it is far better from the P3P. If FPV quality from HDMI output is important, get the P3P. The difference is caused by the lower video bit rate from the camera P3A camera, which saved a few dollars in cost for DJI.

I upgraded to the P3P about 3 months ago, but for the 6 months prior to that I had a P3A and I do have the HDMI board an have flown FPV with both this,

and this,

and having nothing to compare it to - I thought both were amazing...

But now that I have the P3P, I realize that there were dropped frames in the P3A feed and there are almost none from the P3P. It really wasn't something I noticed at the take though. I think you'll find it very useable!

 

[GadgetGuy]

I upgraded to the P3P about 3 months ago, but for the 6 months prior to that I had a P3A and I do have the HDMI board an have flown FPV with both this,

View attachment 57721

and this,

View attachment 57722

and having nothing to compare it to - I thought both were amazing...

But now that I have the P3P, I realize that there were dropped frames in the P3A feed and there are almost none from the P3P. It really wasn't something I noticed at the take though. I think you'll find it very useable!

Nice FPV headsets! I only have the latter... The first costs as much as a P3P! The latter took 4 months to be delivered, after my CC was charged! Very popular!

 

[Tenly]

Nice FPV headsets! I only have the latter... The first costs as much as a P3P! The latter took 4 months to be delivered, after my CC was charged! Very popular!

Well, I got the first one for a very good price ($899 CAD) brand new from Amazon and right after I bought it, the price on the next one jumped to $1299 CAD and then a month later to $1399. (Haven't checked recently).

At the time I bought it (last November) I didn't even realize I could use it for FPV flying. I bought it for watching movies on long flights overseas. I sold my house last October privately - instead of using a real estate agent - and put the $15,000 CAD I saved directly into a budget I could buy toys with - so last November was an awesome month for me! Amazon was at my house nearly every day and it felt like the entire month was one Christmas day after another!

 

[GadgetGuy]

Well, I got the first one for a very good price ($899 CAD) brand new from Amazon and right after I bought it, the price on the next one jumped to $1299 CAD and then a month later to $1399. (Haven't checked recently).

At the time I bought it (last November) I didn't even realize I could use it for FPV flying. I bought it for watching movies on long flights overseas. I sold my house last October privately - instead of using a real estate agent - and put the $15,000 CAD I saved directly into a budget I could buy toys with - so last November was an awesome month for me! Amazon was at my house nearly every day and it felt like the entire month was one Christmas day after another!

Any other interesting toys of note in that December buying spree?

 

[Tenly]

Any other interesting toys of note in that December buying spree?

Ha ha! Yes - pretty much one of everything.

Okay - so I did some rounding in my last message for the sake of expediency - but it was actually about 11,000 I saved by selling the house privately and I made another 10,000 by bundling in an existing HD home theater and a 70" kitchen TV. So my budget was actually $20,000 for toys - but had to include a replacement home theater for the new place.

Other items of note:
- 3D printer
- 27" Retina 5k iMac with 48GB RAM and 1TB SSD
- Home Theater: screen, projector and AV receiver
- Home Theater: leather recliners with electric recline, cup holders and storage
- 28" 4K monitor
- 70" Sharp Aquos
- "Ring" doorbell
- Internet garage door opener
- 64GB Apple TV
- Apple Watch
- 24", 1080p monitor with 4-camera DVR, POE camera security system (Important to mention this one in case some online burglar sees this post as a shopping list!)
- 4TB, external USB3 hard drives (x3)
- 256GB, external, SSD, Thunderbolt hard drive
- accessories for all of the above
- miscellaneous smaller things

It was a very good month...

 

[GadgetGuy]

Ha ha! Yes - pretty much one of everything.

Okay - so I did some rounding in my last message for the sake of expediency - but it was actually about 11,000 I saved by selling the house privately and I made another 10,000 by bundling in an existing HD home theater and a 70" kitchen TV. So my budget was actually $20,000 for toys - but had to include a replacement home theater for the new place.

Other items of note:
- 3D printer
- 27" Retina 5k iMac with 48GB RAM and 1TB SSD
- Home Theater: screen, projector and AV receiver
- Home Theater: leather recliners with electric recline, cup holders and storage
- 28" 4K monitor
- 70" Sharp Aquos
- "Ring" doorbell
- Internet garage door opener
- 64GB Apple TV
- Apple Watch
- 24", 1080p monitor with 4-camera DVR, POE camera security system (Important to mention this one in case some online burglar sees this post as a shopping list!)
- 4TB, external USB3 hard drives (x3)
- 256GB, external, SSD, Thunderbolt hard drive
- accessories for all of the above
- miscellaneous smaller things

It was a very good month...

Awesome list! It would make a very nice haul! I'm not a burglar, but you might want to add a Smith & Wesson firearm to the list, to backup the security system!

 

[kennedye]

Ha ha! Thanks. I'll try too and then we can compare notes.

I actually went down there this weekend with the intention of plotting out some space, and the !@#%?! county has closed it off! (The park is part of a dispute between the neighborhood that wants it preserved and the county that wants it for school land.) I'll look around for a similarly open spot though because now I have to find out for myself.

 

[GadgetGuy]

I think I follow most of this - except it would have been a bit easier if you used y as the height and x as the ground distance to match the conventions I learned in school.... But that's just being picky....

Upon closer examination, it should have been x for the ground distance, and z for the height.

 

[GadgetGuy]

Found this gem on the DJI developer website:

"As an example, DJI's Zenmuse X3 camera has a diagonal field of view of 94°, which is equivalent to a 20mm focal length when using a 35mm sensor. Note, the X3 sensor is smaller than 35mm, and so the physical focal length is also smaller.

A diagonal field of view can be deconstructed to its horizontal and vertical components by using the aspect ratio of the sensor. X3 has a 4000x3000 pixel sensor, and so the horizontal and vertical field of views are 84° and 62° respectively."
Camera Exposure - DJI Mobile SDK Documentation

 

[friar]

Someone needs to go out to a large empty field, put down some colored chalk or something, and start taking measurements!

Oh well, I took a small walk and here are my findings
Pic 1 from Flight paths elevation 500 meters, please do not flame me for elevation, in an experiment the greater the volume the less the error
Pic 2 and Pic 3 visual comparison on google earth and measurement tool gave me 370 X 700 meters.
And according to an ancestor of mine other elevations will produce proportional results

 

[matti]

Your measurement from the mobile screen capture is 700:370 = 1.89 i.e. about 16:9 = 1.78. My calculations (see the spreadsheet earlier in this thread) predict 935 x 526 m image area for that aspect ratio from 500 m.

A test image captured to the SD card with 4:3 should use the whole 94° diagonal sensor and my calculations predict 858 x 643 m image area from 500 m. I haven't yet verified my calculations in practice.

 

[matti]

OK, I did an empirical test with my P3P and compared it to Google Earth. My spreadsheet seems to be correct with 4:3.

But with 16:9 it is not apparently because it incorrectly assumes 94° diagonal also with it.

4:3 and 16:9 have the same X width but 16:9 crops Y height.

 

[matti]

I updated the spreadsheet earlier in this thread to correct the error in 16:9 calculations.

I empirically tested the results with my P3P and the figures seemed to be in the same ballpark.

From 500 m the coverage should be:

858 x 643 m @ 4:3
858 x 483 m @ 16:9

 

[Wolfiesden]

Oh well, I took a small walk and here are my findings
Pic 1 from Flight paths elevation 500 meters, please do not flame me for elevation, in an experiment the greater the volume the less the error

500m? What 500m? Whacutalkinbout Willis? I didn't see a thing

 

[friar]

Yes dear, 500m vertically from take-off position but always only 100m (horizontally) away from terra firma next to a cliff.

 

[Drbrand]

Hi. I've skimmed through the posts here. Ive had the same problems on my farm in Namibia. How wide apart can I make transect/ grid lines to save batteries on my p4p. I went to my closest tar road. Using a tape measure i measured the white stripes on the road and the spaces between. I then put the drone in the air and using litchi program i put the grids and diagonals on my screen ( samsung tab a). Using the cross as the centre point i went up to 10 m straight above the road ( no traffic out here), and with the road running left to right. Levelling the tar road between the grid and putting the diagonal cross centre on the road i took a picture. Then i went up toe 20 m and then up to 30 and so on until i reached 100. I then took the sd card out and put it in my tablet. I counted the stripes and spaces between stripes and did some maths. I also did this with the road running from top to bottom. Is anybody interested in checking my work? And correcting what ive done wrong?

 

[GadgetGuy]

Hi. I've skimmed through the posts here. Ive had the same problems on my farm in Namibia. How wide apart can I make transect/ grid lines to save batteries on my p4p. I went to my closest tar road. Using a tape measure i measured the white stripes on the road and the spaces between. I then put the drone in the air and using litchi program i put the grids and diagonals on my screen ( samsung tab a). Using the cross as the centre point i went up to 10 m straight above the road ( no traffic out here), and with the road running left to right. Levelling the tar road between the grid and putting the diagonal cross centre on the road i took a picture. Then i went up toe 20 m and then up to 30 and so on until i reached 100. I then took the sd card out and put it in my tablet. I counted the stripes and spaces between stripes and did some maths. I also did this with the road running from top to bottom. Is anybody interested in checking my work? And correcting what ive done wrong?

P4P has a narrower FOV (84°) than the P4 and the P3P (94°), so you will require more photographs from the same elevation.