空拍機攝影淺談(The Unnamed Aerial Vehicle (UAV) Photography)

空拍機攝影已發展許多年,近來己有愈來愈流行的現象,但缺點是空拍機的相機感應器太小只適合光線良好的環境,如在光線較暗的環境如日出或夕陽時影像會有較多的雜訊,市場上雖也有可攜帶單眼相機的空拍機,但那些都屬於商業用途非在一般玩家使用的範圍, 在此慬來談談一般玩家及業餘愛好者在空拍機操作、影片/照片拍攝及後製上的一些個人的経驗和內容。

目前空拍機的市場上,中國大彊先進(Dji)是全球市場上佔有率最高的產品,Dji空拍機的種類涵蓋了大型商用及一般玩家等各種不同的用途及須求的產品,目前市場上以Mavic pro 、Mavic air 2s 、Mavic mini2等為大宗,至於其他也在市場上有相當佔有率的有Parrot anafi 、美製Autel䓁,近年來空拍機的品牌如雨後春筍般的擁入市場,但大多數使用者均以”遙控飛行”遊玩為大部分,從事業餘或職業攝影的空拍並不多,個人從事攝影多年現則將部份拍攝工作使用空拍,空拍攝影有別於在地面拍攝,從高空的視角呈現的風景影像有更廣闊、立體的效果,現以個人使用及操作空相機在攝影上的心得和経驗簡介分享如下:

The drone photography have been developed for years, and it is becoming more popular nowadays, but because of the small sensor of the drone camera there are more noise in the image, it is good for taking images under bright ambient light but not in the low light situation, such as at dawn and sunset, although there are drones for photography in the market which can equipped with the DSLR camera for high grade images, but they are mainly for commercial use not for the hobbyists and amateur photographers in the consumer market, as a amateur photographer, I would like to share my experience of the drone flying in this area as the follows:

Dji, a Chinese based company has the most market shares in the consumer drones market, their products covering in both commercial and hobbyist usage, their drones for the consumer market mainly are Mavic pro (now Mavic pro 3) 、Mavic air 2s 、Mavic mini2, the other main competitors now in the market are Parrot from France and Autel from America etc., but there more products have been joining the market, most of them are for the FPV(first personal view) flying and not much for the aerial photography, as a photographer for years, I now have extended my photography by using drone camera, taking photos from the air provide wider prospective and 3D dimensional effect images, below are my experience in the usage and photo taking by drones:

一. 空拍機的選擇:

  1. 空拍目的:選購空拍機以前要確定使用的目的,例如是要遙控飛行遊戲、拍攝空照影像或是旅遊攝影等,因為不同的目的所選擇的空拍機在價格上有很大的差別,如要從事空拍攝影則鏡頭的感應器大小及夜間感光能力就很重要價格也較貴,如要進行旅遊攝影那空拍機的機型大小和重量則是選擇重點必須要能攜帶方便,尤其是遠程的旅行,至於以遙控飛行遊戲為目的的則可選擇價位不高的所謂FPV(即穿越式)空拍機,以第一人視覺來遙控飛行,着重的功能是要有高速飛行能力並有跟拍、螺旋槳防䕶及防撞功能。
  2. 機種選擇:
    1. 空拍攝影:
      1. 大疆(Dji):目前最新的機種包括Mavic pro 3、Mavic Air 2、Mavic Mini 2等
      2. 蓓洛(ParrotParrot anafi
      3. 阿泰爾(AutelAutel EVO 3
    2. 旅遊攝影
      1. 大疆(Dji):Mavic Mini 2
      2. 蓓洛(Parrot)::Parrot anafi
    3. 遙控飛行
      1. 大疆(Dji):Dji FPV
      2. 蓓洛(Parrot):Parrot FPV
      3. 史開狄奧SKydioSKydio 2
  3.  網路最新資料搜尋:在網際網路上例如google、Youtube等,每天都有許多相関熱心的玩家/專家等提供的各種空拍教學知識或秘訣,對初學者在空拍機使用或操作上都有很大的幫助。

. 飛行操作及注意事項

  1. 熟悉空拍機規格/性能每個品牌的空拍機都有其不同的規格,如電池電壓、飛行時間、飛行速度、最大耐風度䓁,另外每個品牌在訊號傳輸距離、防電磁波干擾能力等也各有不同特奌,各品牌也有不同的自主飛行功能:包括目標自動追蹤、跟隨功能、目標航奌自動飛行䓁,若以拍照或攝影為主要目的則應注意像素、鏡頭的規格,尤其在低環境光線下的感光能力。
  2. 飛行前檢查:在從事空拍攝影或飛行前須進行一些飛行前檢查程序包括:
    1.  飛行環境氣候:飛行環境注意項目包括:天氣、溫度、風速、陣風、降雨概況、雲覆蓋率、能見度、可見的衛星數、磁場干擾、衛星鎖定等
    2. 地奌選擇:飛行地點應選擇以空曠無障礙物 (如建築物或林木密集、電力輸送塔等)的地區並遠離人群。
    3.  空拍機檢查:
      1. 電池電壓:空拍機電池一般都是使用體積小儲電量大的智能型鋰電池LiPo (Lithium Polymer battery),它具備智慧電路控制、充放電操作等功能,並以指示燈顕示電力狀況,正確使用方法是在飛行前將電池充飽電,使用時放電至約20%電量,若須長時間儲放時則充電至滿電量的60%,使用鋰電池的注意事項是放電時勿使用至電池容量低於約20%,同時也避免將電池充滿電儲放(將電池充飽儲放會縮短電池壽命),另外電池內的化學物質也易因外力的撞擊而燃燒。
      2. 羅盤校正:因應變更不同飛行地點產生的飛行方位差異,有須要時應調整空拍機的羅盤方位,每次起飛前作羅盤校正可防止飛行中產生異常狀況。
      3. 機身檢查:飛行前檢查空拍機的各部零件包括外觀及移動部份都在正常位置
      4. 螺旋漿檢查:檢查外顴及螺絲固定狀況。
  3. 飛行中注意事項:
    1. 自動返航至起飛點的設定(一般空拍機起飛時內部會自動記憶起飛點位置)。
    2. 注意飛行地區周遭的障礙物如建築物、林木、輸電線塔等。
    3. 自動返航的高度設定。
    4. 注意遙控器與空拍機的連線狀況(遙控器應面向空拍機)。
    5. 意外發生時應立即啓動自動返航功能。
  4. 安全規則:
    1. 禁航區(如機場、軍事基地等)的資料收集可參考AirMap網站。
    2. Dji空拍機均內建嚴格的限航區域(紅區限航,黃區限高)。
    3. 避開人群聚集及密集的建築物區域。
    4. 飛行距離應以目視可及為原則。
    5. 如空拍機重量超過250公克須取得飛行操作執照

三. 照片拍攝:

  1. 相機設定:由於空拍機的光圈及焦段除一些商用或髙檔機種外都為固定,因此只須設定以下的項目:
    1. 白平衡:由於相機自動白平𧗽會因環境光線的不同產生變化,因此建議使用手動設定。
    2. iso值:光線許可下應設定最低值以取得較好的畫質。
    3. 快門速度:光線許可下應提高快門速度增加影像的銳利度。
    4. HDR功能:相機在拍攝時會依環境光線亮/暗分佈來增減調整影像曝光呈現畫面適當的明暗度。
    5. 減光濾鏡:當環境光線很強時受光線散射的關係,影像色彩和對比會因反光而變的平淡不立體,使用減光鏡可遮蔽散射的光線,使影像的色彩回復飽和鮮豔。
  2. 拍攝高度:視拍攝的目的和現場景觀而定,但空拍的優勢即是高度及視角,因此很多影像的視角是採取90度向下或向上(目前僅法製蓓洛空拍機可鏡頭可向上90度)拍攝。
  3. 影像後製:由於空拍機相機的影像感測器較小,因此能獲取的光線資料比較一般單眼相機少,因此可修飾的部份不多,在影像後製上無須做過多的修飾,以免影像呈現出不自然,只須在光線、對比及鋭利度上做些加強即可。

新北市蝴蝶景觀公園360度全景(Parrot anafi 空拍機)

老梅石槽海岸夕陽(Dji mini2空拍機)

古亭河濱公園夕陽(gopro空拍機)

四. 影片拍攝:

  1. 相機設定:
    1. 白平衡:如果是在一固定時段下拍攝,環境光線色溫變化不大時,應手動設定白平衡(如陽光色溫為5300-5500K),使影片色溫呈現一致。
    2. iso值:設定低值以減少影片旳雜訊。
    3. 快門速度:一般為每秒照片數(fps)乘以2即1/48或1/60秒。
    4. HDR功能:使用此功能時可增加明/暗灰階,使影片呈現亮暗平衡而不須太多後製時的修飾。
    5. 減光濾鏡:在錄製影片時減光濾鏡是不可或缺的工具,因為影片的規格一般是由每秒24或30照片(fps)組成,因此快門速度的設定為fps乘以2即1/48或1/60秒所録製的影片能呈現出自然順暢,但在較強的環境光線下快門速度提高時,在鏡頭快速運動時則影片會呈現不自然的抖動,此時須安裝減光鏡來降低快門速度。
  2. 拍攝高度:拍攝髙度應視所要拍的視角及畫面的安排,一般高度愈高視角及視界愈廣較有利於後製的剪裁舆修飾。
  3. 影像後製:空拍影片的後製與一般的影片後製相同,影片的剪裁及創意剪接是完成一部生動影片的要點。

五. 影像後製:空拍影像後製由於相機感應器小,對光線收集能力差,因此應注意雜訊状的修飾, 由於光線資料不足修圖時不要在飽和或稅利度上作過度修飾以免產生不自然的現象,重點應在加強亮/暗的對比上以彰顕影像的立體感。

1. How to select drones:

  1. The purpose of using drones: You need to decide the purpose to fly a drone, such as flying for funtaking aerial photo or video or travel photography, there are cost difference between your purpose to fly a drone, for example if you want to fly drone for photography, the drone’s camera sensor size and the low light ability are essential the costs are also high, if the drone flying is for travel then the size and weight of the drone are important, it needs easy to carry, especially when you travel in distance, as to the flying for fun then you need a FPV (Fist Personal View) drone, which should have high speed (fast) ability and follow or tracing function, also with prop protection accessory etc., normally the cost is not high.
  2. The selection of drones:
    1. Photography drones:
      1. DJI: the most popular models are Mavic pro 3、Mavic Air 2、Mavic Mini 2 etc..
      2. Parrot: Parrot anafi
      3. Autel: Autel EVO 3
    2. Drones for travel:
      1. DJI: Mavic Mini 2
      2. Parrot: Parrot anafi
    3. FPV drones:
      1. DJI: Dji FPV
      2. Parrot: Parrot FPV
      3. Skydio: Skydio 2
  3. New trend of drones on the internet: In the internet such as Google、Youtube , there are a lot of posts on the drone flying introductiontutorial and hints, there can be a big help for the beginners and also the experienced drone pilots.

    2. The precaution and pre-flight procedure:

    1. Well familiar with the specification and function of the drone: there are different specifications among the drone brands such as battery voltage、flying time power against wind speed etc., except, there are also different function and advantage between brands, like data transitscommunication distanceanti radio interferencethe autonomous ability including tracing and following the target way points fly planning etc., for aerial photography the image sensor size and resolution of the camera are essential specially the dynamic range ability in the low light situation.
    2. Pre flight check:
      1. Preparing the fly:
        1. Weather condition: The weather checklist are including temperature、 wind(m/s) gusts(m/s) dry or rain cloud cover visibilitysates located Kp value sates visibility etc., can refer the app “UAV Forecast”.
        2. Location: the flying location should be wide open without barriers, such as buildings、woods and power towers etc., most important is to be away from the human gathering area.
        3. Drone check:
          1. Battery power: Now modern drones are using the Lipo battery which has the ability of high volume storage and small size with smart circuit to control the battery behavior, and also provide the indication displaying the status, the correct to operate the Lipo battery are store it in about 60% of total power and exhausting it till 20%, when storing battery for a long period, it should be charged about 60% of total volume, storing the fully charged battery can damage the battery life, also do not over discharge the battery, the chemical material in the Lipo battery can be dangerous from the outside striking.
          2. Compass calibration: Fly in different locations it can be a compass error owing to the radio interference, so it is always better to calibrate the compass before flying.
          3. Drone body check: This is a important item in the pre-flight check list, making sure the appearance of the drone is normal and the moving parts are tired and moving freely.
          4. Propeller check: checking the appearances of the props and retie it.
    3. In flight check:
      1. Set the RTH (return to home) point just after the drone launching, normally the advanced drones are all have the build-in home point acknowledgement.
      2. Watch and away from the obstacles like buildings、trees and power lines towers etc. during the flying.
      3. Making sure the height setting of RTH not encountering the obstacles.
      4. Bewaring the connection between the drone and controller, always facing the controller to the direction of the drone.
      5. Any error message or abnormal movements happened, starting the RTH function immediately
    4. Safety rules:
      1. Have to fly avoiding the restriction fly zone ( airports, military facilities etc. ), there is an app “AirMap” can be the reference.
      2. The Dji drones have the build-in restriction firmware to limit the flying in the restriction area ( red zone: no flying, yellow zone: height limit )
      3. Avoid flying over the human crowd and the high building density area.
      4. The flying distance should be in the eye sight.
      5. You need to apply an operating license for a drone over 250 grams.

    3. Photo taking:

    1. Camera setting: Since the camera on the drone are normally with fixed exposure and focus range except some advanced ones, so the setting won’t be too much complicated, the main parts are as the follows:
      1. White balance (Kevin) setting: In the auto mode, the white balance can be switched owing to the different ambient light, so a fixed white balance setting offers a constant color temperature.
      2. ISO setting: For a better image quality, the ISO value should be as low as possible.
      3. Shutter speed: Setting a higher shutter speed when the ambient light allowed can result a more sharp image.
      4. HDR function: This function can offer a proper dynamic range to meet the ambient condition resulting a better exposure of the image
      5. Neutral density (ND) filter: In the strong lighting condition, the image color and contrast can be washed out because of the light diffusion, this can be improved by adapting a ND filter, which can block the diffused light and recovering the contrast and color
    2. Shooting height and prospect: It depends on the purpose of shooting, the advantage of the drone photography are more freely the shooting height and prospective angle, the Parrot anafi is the only drone which can shoot 90 degree up and down.
    3. Post processing: Since the small drone image sensor, which don’t have the ability collecting enough ambient light, normally doesn’t need too much efforts to do the post processing, otherwise the image will become unnatural, the important points in the post processing are on the contrast、color saturation and sharpness.

    360 degree spherical view (parrot anafi)

    Riverside park Sunset (Dji mini2)

    Riverside park Sunset (Gopro karma)

    4. Video taking:

    1. Camera setting:
      1. White balance: In a certain period of a day, the ambient color temperature tend to be consistent, normally it will be around 5300-5500K, so with a setting of manual white balance can have a more consistent color temperature in video.
      2. ISO setting: The low IOS value is better for the quality of the video.
      3. Shutter speed: Normally the shutter speed for taking video is 2 times of the frame rate ( 24fps or 30fps ) that is 1/48 or 1/60s.
      4. HDR function: The HDR function in taking video can offer more dynamic range for a better lighting video quality, and less post processing needed
      5. Neutral density (ND) filter: the ND filter is a must accessory for a better video quality to get a smooth and natural video, the setting of the shutter speed should be 2 times of the video frame rate, that is 48fps or 60fps, but under the strong lighting scenario, we need to set a higher shutter speed to against the lighting blown out, then the video will become jittery and unnatural, so to put on a ND filter to lower the shutter speed to reach the correct fps.
    2. Shooting height and prospect: It depends on the plan of shooting, taking video in a higher altitude and wide prospective can be easier for the post processing.
    3. Post processing: The aerial video post processing is the same as the normal video, the important idea is the creation in trimming and cutting in the clips.

    5. General post processing of the drone images: Because of the small drone sensor, there are not much ambient data in the image, the overall post processing for the images or video in the aerial photography should be easy and not too many steps in the saturation and sharpness adjusting, avoiding the odd or unnatural results, the important points are to improve the dynamic range and emphasis the contrast showing a more 3D images.