Q&A: before you begin
Before you do anything, lets start with a few questions to help guide your path and utilize these methods correctly to achieve your analysis objectives.
A clear understanding of the anticipated conditions of your study and expected outcomes is always a good place to start. Qualitative analysis using high resolution 4800 DPI scanning has a high degree of utility in certain situations, but as percent coverage increases, it becomes progressively less insightful. High resolution imaging takes more resources in both collection and analysis time compared to lower resolution scans, so consider the following decision tree when considering use of this method:
- Is there a reason to know information about very small droplet stains (sub 100 micron diameter) in the study's deposition?
No: The methods detailed here may still be used, but other software such as Depositscan, Stainalysis, or other analysis packages (see resources Page) may be easier for processing. Links to these are provided toward the end of this report but they are not discussed further here.
Yes: Continue
2. Will three-dimensional canopy be analyzed?
No: Without vertical or other three dimensional stratification of the collectors there is usually a lower degree of variation among the collectors. High resolution analysis may be less useful.
Yes: In three-dimensional canopy spraying, it is typical to have 2-3 orders of magnitude variation or more between minimum and maximum deposition. 4800 DPI Scanning can provide highly relevant insight; especially in the collectors that exhibit minimum coverage (see section on post-processing).
3. What droplet spectra will be sprayed?
>250 Micron VMD (ASABE S572 Coarse and coarser sprays) the volume fraction of fine droplets (under 150 microns) typically becomes small in these ranges. Assuming the stains will have some spread factor, lower resolution imagery may be adequate for this range of spectra. The exception would be if it were desired to image the small drop stains specifically, such as in a 3d canopy study. Some sort of pre-processing separation of high and low coverage cards may be useful.
<200-250 Micron VMD (ASABE S572 Medium Sprays and finer) 4800 DPI scanning becomes increasingly suitable as the spectrum becomes finer.
4. Is there a reason to know information about very small droplet stains (sub 100 micron diameter) in the study's deposition?
<15%: 4800 DPI resolution is likely to provide useful information, especially in evaluating hits per unit area.
>15%: Unless information on droplet fines is specifically sought or the qualitative analysis is comparing hits per unit area rather than percent area covered, the small stain fraction will contribute little statistically to the overall analysis. Attempting hits per unit area analysis at coverage over 15% begins to become difficult and of questionable/diminishing value, as stains are often composed of multiple hits and tend to connect.